Ace Rankings for Each MLB Team's Best Starting Pitcher

With fresh rankings for the top starting rotations in Major League Baseball out of the way, the next step is right there like a hanging slider.

That's right. It's time to rank the aces.

The first step was to determine which pitcher is the de facto No. 1 on each team's staff, which didn't necessarily mean taking Roster Resource's word for it. It was more instructive to ask: "Who's carrying the rotation right now?"

Ranking the 30 pitchers was partly a matter of considering their track records, but more so how they're performing this year. If they're having a strong season, good. If they're hot, even better. If it all ties in with their previous work, better still.

Ultimately, it was about finding an order that just feels right.

Age: 30

2023 Stats: 24 GS, 129.0 IP, 153 H (23 HR), 83 K, 37 BB, 5.02 ERA

In Kyle Freeland's defense, the 4.68 ERA he has at Coors Field for the year is pretty good. As in, "nearly a full run better than the league average" good.

Freeland is nonetheless trending backward, both in the sense that he's not replicating his respectable performances from 2020-22 and that he's in a slump. He's pitched to a 6.62 ERA in his last 10 starts, in which he's been hit at a .336 clip to boot.

Obviously, nobody can fault the lefty for not throwing strikes. But when you're a guy with an 89 mph fastball and no wipeout secondaries, there's only so much you can do.

Age: 27

2023 Stats: 25 GS, 134.2 IP, 127 H (28 HR), 127 K, 35 BB, 4.61 ERA

It's a thankless job, being the ace of the Oakland A's. You can tell by how Sears' record is 2-10 even though he hasn't been that bad.

Indeed, the lefty does a few things well. So long as one ignores his MLB-high 14 hit-by-pitches, his walk rate reflects his strong control. And even if he's only recently realized it, he has a pretty good slider.

As far as what Sears doesn't do well, half of those 28 home runs have come off a fastball that has decent velocity but not much movement. He's also been cold of late, posting a 6.91 ERA over his last six outings.

Age: 27

2023 Stats: 25 GS, 139.1 IP, 147 H (15 HR), 119 K, 43 BB, 5.04 ERA

Brady Singer enjoyed a quiet breakout in 2022, deploying a strong sinker-slider combination to pitch to a 3.23 ERA over 153.1 innings.

If the question is what's eating him in 2023, suffice it to say that half that combo has been on the fritz. He's lost 1.4 mph in average velocity off his sinker, against which opposing hitters have gone from a .255 average to a .313 average.

On the plus side, the righty has stabilized with a 3.45 ERA and an average of 6.2 innings over his last 10 starts. He's been more trusting of a slider that's recovered from its own time on the fritz in the first month of the year.

Age: 27

2023 Stats: 26 GS, 138.0 IP, 132 H (14 HR), 163 K, 63 BB, 4.50 ERA

Though he finished second to Justin Verlander in the Cy Young Award voting, it was indeed Dylan Cease who led American League hurlers in rWAR last year.

It looked out of the gate like the mustachioed righty had more where that came from, as his first four starts yielded a 2.01 ERA. What's instead unfolded since then is a long, sustained slog marked by a 4.98 ERA.

That Cease has lost 1.3 mph off his fastball hasn't helped, though it more so stands out that he hasn't bamboozled hitters with his slider like he did in 2022, when it was by far the most valuable pitch in baseball. In any case, it's been a rough step back.

Age: 35

2023 Stats: 27 GS, 152.1 IP, 167 H (16 HR), 107 K, 31 BB, 4.55 ERA

Miles Mikolas was an All-Star in 2022 and he perhaps deserved at least one Cy Young Award vote upon finishing the year with a 3.29 ERA over 202.1 innings.

As he's retaining an elite walk rate, Mikolas still resembles his '22 self to one extent. But to all others, not so much. His sinker has endured an especially painful downfall, and one that he can't necessarily blame on the weird regression of the Cardinals defense.

Yet Mikolas' season is also unfairly colored by a small handful of bombs, especially at the outset. If his season had started on April 16, he'd be sitting on a more respectable 3.98 ERA.

Age: 29

2023 Stats: 26 GS, 148.0 IP, 135 H (27 HR), 159 K, 53 BB, 4.32 ERA

Alas, Shohei Ohtani won't be capable of fulfilling his role as the Angels' ace for the rest of the year. For the second time since 2018, he has a torn UCL.

It's now up to trade-deadline newcomer Lucas Giolito to carry the Angels rotation, which would be an acceptable proposition if he was living up to his status as a three-time receiver of Cy Young Award votes. Instead, he's mired in a seven-start slump marked by a 7.07 ERA.

Hitters are just more comfortable in the box against Giolito than they were between 2019 and 2021. It shows in both his diminished chase rate and in how hard he's been hit within the strike zone the last two years.

Age: 30

2023 Stats: 19 GS, 113.0 IP, 95 H (10 HR), 115 K, 27 BB, 3.03 ERA

Availability should be a defining feature of an ace, so it can't be ignored that Eduardo Rodriguez missed more than a month with a finger injury.

But coming on the heels of a year that was rough both professionally and personally, this season has nonetheless been a happy occasion for Rodriguez. He's on track for new career bests for ERA and Fielding Independent Pitching.

As far as how to explain it, this is a guy who's always had good command and who has regained fastball velocity and is unsurprisingly missing more bats. The only catch, really, is that he hasn't been as effective in pitching to a 4.37 ERA since coming off the IL.

Age: 25

2023 Stats: 25 GS, 135.2 IP, 129 H (18 HR), 118 K, 67 BB, 3.85 ERA

Josiah Gray only did one of the three true outcomes well in 2022, striking out more than a batter per inning but leading the National League in walks and home runs.

His All-Star turn this year can largely be traced to how he's basically cut his home run rate in half. The fix was simple, as he's taken a fastball responsible for 24 of last year's 38 homers and turned it into a secondary offering in deference to his slider.

However, the gas that led Gray to a 3.30 ERA through June 30 has run a bit low. He has a 5.13 ERA in eight outings since then.

Age: 27

2023 Stats: 26 GS, 155.2 IP, 152 H (19 HR), 173 K, 47 BB, 4.22 ERA

Whereas he was formerly a top prospect turned major league bust, Mitch Keller suddenly began a year-long run as one of baseball's best pitchers in July 2022.

Over 34 starts between the 11th of that month and July 8 of this year, Keller logged a 3.06 ERA over 200 innings. It was in part a sweeper-driven breakout, as he got in on the craze by making the pitch his primary breaking ball and benefited accordingly.

Alas, Keller's breakout has stopped dead in its tracks. He's been crushed for a 6.98 ERA over seven starts since the All-Star break, in which his sweeper is but one of several pitches that haven't been as effective.

Age: 24

2023 Stats: 15 GS, 85.1 IP, 69 H (12 HR), 93 K, 31 BB, 3.16 ERA

Hunter Greene is nominally the ace of the Reds again now that he's back off the injured list, but the role truly belongs to Andrew Abbott. He's been the second-most valuable pitcher in the National League since his June 5 debut.

Heck, he hasn't even been scored upon in a third of these outings. He's mainly silenced hitters with a sweeper that bears a minuscule .106 average, though his four-seamer and changeup also grade as above average offerings.

The only thing keeping Abbott from world domination is a platoon split. He's silenced lefties to the tune of a .514 OPS, but righties have him figured to that of a .726 OPS.

Age: 24

2023 Stats: 20 GS, 113.2 IP, 101 H (11 HR), 112 K, 36 BB, 3.01 ERA

With Shane Bieber and Triston McKenzie on the IL and Aaron Civale having been traded to the Rays, the Guardians rotation is in the hands of their next generation of prized hurlers.

Out of Tanner Bibee, Gavin Williams and Logan Allen, Bibee boasts the most experience and the most success. He's allowed more than three earned runs in just two of his 20 starts, and he's on a heater with a 2.34 ERA in his last 11.

Bibee's fastball averages 95.1 mph and seems to get on hitters even faster, and his slider is a two-plane breaker that's held hitters to a .208 average. If his changeup ever becomes a better weapon against lefties, watch out.

Age: 24

2023 Stats: 21 GS, 119.1 IP, 119 H (17 HR), 100 K, 31 BB, 3.70 ERA

It's fair to have a sense that Brayan Bello recipe for success isn't sustainable. After all, it's not like he specializes in missing bats or even managing contact.

But if nothing else, it's refreshing to see a 24-year-old with a walk rate in the 81st percentile. And the righty's stuff definitely passes muster, specifically regarding his 95.0 mph sinker and what might be the best changeup possessed by any starter.

Despite some stumbles since the All-Star break, Bello has been racking up strong starts for a while now. Since the start of June, he's averaged 6.2 innings with a 3.60 ERA over 11 outings.

Age: 26

2023 Stats: 23 GS, 127.2 IP, 106 H (12 HR), 122 K, 35 BB, 3.03 ERA

If this was a list of the most overlooked good pitchers in baseball right now, Kyle Bradish would have a strong case for the No. 1 spot.

It's not just that he ranks fifth among AL hurlers in WAR. He's also been warm for months, with a 2.49 ERA and .205 average against in 15 starts dating back to May 28.

This is pretty good stuff for a guy whose four-seam fastball is among MLB's worst, but he's long since adjusted by making his slider into his primary pitch. Both that and his curveball are among the league's best breaking balls, which is to say nothing of how much pitch modeling metrics like them.

Age: 29

2023 Stats: 24 GS, 138.1 IP, 123 H (15 HR), 136 K, 19 BB, 3.58 ERA

Shane McClanahan, Drew Rasmussen and Jeffrey Springs are done for the year, and it's hard to refer to Tyler Glasnow as an ace while his own durability remains suspect.

Hence the default to Zach Eflin as the Rays' No. 1, though this is hardly meant as an insult. His ERA has yet to go higher than 3.67 and his Baseball Savant page is teeming with red (i.e., above average) figures.

There's also something just satisfying about a guy who has a 98th-percentile walk rate and a 92nd-percentile chase rate. That's a guy who not only knows the strike zone, but also knows how to make hitters expand it.

Age: 30

2023 Stats: 23 GS, 129.2 IP, 101 H (12 HR), 154 K, 61 BB, 3.19 ERA

The $500 million the Mets spent in free agency last winter hasn't proven to be a good investment, but at least they're not being haunted by Kodai Senga.

There's your obligatory nod to the "ghost fork", which has been as advertised and then some. The results against it include a .128 average, 81 strikeouts and zero home runs, all of which give it a case as the best pitch in MLB today.

Between his walks and NL-leading 11 wild pitches, the ball does tend to get away from Senga. The longtime ace of the Softbank Hawks has nonetheless been overpowering since Day 1, and increasingly so as he's pitched to a 2.72 ERA in his last nine starts.

Age: 35

2023 Stats: 18 GS, 105.1 IP, 82 H (14 HR), 111 K, 26 BB, 2.48 ERA

Once again, availability matters. And Clayton Kershaw's has often been spotty over the last decade, including when he missed over a month this year with a shoulder injury.

It's otherwise hard to knock a guy who leads all active pitchers with a 2.48 ERA and every pitcher ever with a 157 ERA+. Even Kershaw's fallen velocity is less of a story this year, and his walk and home run rates are still good despite regressing from last year.

Though pitches usually rise and fall, Kershaw's slider has remained a mainstay among the best of the best. And injury absence notwithstanding, he last allowed more than two runs in a start back on May 27.

Age: 39

2023 Stats: 23 GS, 131.1 IP, 112 H (24 HR), 151 K, 39 BB, 3.77 ERA

It does feel weird to label Max Scherzer as the Rangers' ace after just four starts, but them's the breaks with Jacob deGrom out for the year and Nathan Eovaldi also injured.

Whatever the case, the three-time Cy Young Award winner has looked more like himself of late. Both in the sense that his fastball velocity and his whiff rate have perked up since the beginning of the year, and in that he's been hot with a 2.68 ERA since the All-Star break.

Mind you, the Scherzer of today is still not to be confused with peak Scherzer. But when even the watered-down version of a guy is this good, that guy must be special.

Age: 28

2023 Stats: 23 GS, 132.0 IP, 126 H (10 HR), 127 K, 28 BB, 2.80 ERA

Justin Steele's All-Star breakout was on pause for a couple weeks because of a forearm injury, but you'd never know it. He had a 2.65 ERA before and he has a 2.95 ERA since.

That Steele's four-seamer is one of the most valuable fastballs in MLB doesn't square with his 24th-percentile velocity, but Zach Crizer of Yahoo Sports wrote the book on its unusual deceptiveness. It's a mutant pitch, and that's meant as a compliment.

Basically the only other offering in Steele's repertoire is a slider that's especially useful against lefty batters, who are hitting .193 against it. It's a relatively straightforward recipe for success, but a 2.98 ERA since the start of last year ultimately doesn't lie.

Age: 33

2023 Stats: 25 GS, 143.0 IP, 123 H (5 HR), 147 K, 50 BB, 3.15 ERA

Sonny Gray was plenty good in his first season with the Twins in 2022, but his availability was limited. He logged only 24 starts and 119.2 innings in the process of posting a 3.08 ERA.

It's good on him that he's already surpassed the former and far surpassed the latter in 2023, wherein he's had every one of his five primary pitches working. And none more so than his sweeper, which is responsible for a .121 average, 82 strikeouts and zero homers.

In all, squaring Gray up is one of the hardest things to do in baseball right now. The .314 slugging percentage he's allowed ranks second among qualified starters.

Age: 27

2023 Stats: 26 GS, 171.0 IP, 160 H (21 HR), 144 K, 44 BB, 4.16 ERA

Sandy Alcantara's 2022 season was a brilliant anachronism. He maintained a 2.28 ERA even as he pitched 228.2 innings with more complete games on his than any other team had.

Perhaps down was the only way the reigning Cy Young Award winner could go in 2023 and, well, that's what's happened. Opposing hitters deserve their share of the credit, if for no other reason than they've flipped Alcantara's changeup from unbeatable to very beatable.

Yet Alcantara has looked more like his '22 self lately. Since his ERA was last over 5.00 on June 21, he's made 11 starts and logged a 2.99 ERA over 75.1 innings. Among other things, he's simply had better velocity.

Age: 24

2023 Stats: 25 GS, 146.1 IP, 112 H (18 HR), 227 K, 46 BB, 3.57 ERA

Here's the nutshell synopsis of Spencer Strider's rise over the last two seasons: despite ranking 43rd in innings pitched, he ranks first in strikeouts.

His strikeouts-per-nine rate has indeed only risen even as he's been tasked with handling more work this year, for which it's helped that he's been somewhat less reliant on his fastball. An increase in sliders has translated to more chases and, naturally, more whiffs.

So why has Strider had a handful of duds while pitching to a modest 4.11 ER since June 8? It seems those who would sit fastball have the right idea, as he's still throwing it nearly 60 percent of the time even as it's become a liability.

Age: 28

2023 Stats: 26 GS, 158.0 IP, 114 H (19 HR), 160 K, 56 BB, 3.65 ERA

Between Aug. 18, 2020 and the end of the 2022 season, Corbin Burnes was nothing less than MLB's best pitcher as he racked up a 2.60 ERA over 412.2 innings.

He hasn't been that guy for much of this season, for which the explanations aren't hard to spot. He's lost velo on his fastball and both his strikeout and walk rates have taken turns for the worse.

Burnes has, however, put himself on a path to salvage with a 2.97 ERA in 10 outings since the start of July. And his overall numbers generally belie what it's been like to actually try to hit him, as he ranks third in average against and fifth in slugging against.

Age: 29

2023 Stats: 24 GS, 154.2 IP, 136 H (16 HR), 153 K, 38 BB, 3.55 ERA

It should perhaps be Justin Verlander here to represent the Astros, but Framber Valdez was there first and he's been the more productive pitcher throughout the year.

Some of Valdez's numbers raise the question of how anyone ever gets on base against him. His walk rate has never been better in a full season, and he's also striking out about a batter per inning with a top-five ground-ball rate. No wonder he threw that no-hitter on Aug. 1.

Yet even despite that no-no, Valdez is slumping in the second half. He's posted a 6.68 ERA in seven starts, in which both strikeouts and ground balls have been harder to come by.

Age: 30

2023 Stats: 26 GS, 157.1 IP, 126 H (23 HR), 175 K, 37 BB, 3.15 ERA

Luis Castillo is nothing if not consistent. In 137 starts for the Reds, he was 25 percent better than average. In 37 starts for the Mariners, he's been...25 percent better than average.

This is not to say Castillo hasn't changed. It used to be his changeup that was unhittable, and now it's a four-seam fastball that's among the poster boys for Vertical Approach Angle. After hitting .151 against it last year, batters have modestly improved to a .161 average in 2023.

This season is also on track to be Castillo's new high-water mark as an innings eater. The three-time All-Star is averaging 6.1 for the year, and he's fallen short of six frames exactly once in his last 11 outings.

Age: 33

2023 Stats: 25 GS, 151.0 IP, 137 H (14 HR), 165 K, 30 BB, 3.70 ERA

After finishing second in an NL Cy Young Award race he arguably should have won in 2021, Zack Wheeler's velocity took a dive in 2022 and has yet to recover.

It doesn't matter. Pitch modeling metrics still love Wheeler's stuff, and every single one of his key peripheral stats at Baseball Savant still grades as above average. He's a rare pitcher who throws tons of strikes and gets whiffs and avoids hard contact.

Wheeler has also been rolling for a while now. Since a seven-run dud on June 2 pushed his ERA above 4.00, he's pitched at least six innings in 11 of his 13 starts and logged a 3.17 ERA in the process.

Age: 26

2023 Stats: 26 GS, 169.0 IP, 158 H (18 HR), 162 K, 26 BB, 3.36 ERA

Logan Webb came out of the gate in 2021 in uninspiring fashion, allowing 19 earned runs through his first 32 innings for a 5.34 ERA. It was not the best of times.

It was immediately after this, however, that Webb became one of the best pitchers in baseball. His last 78 starts have yielded a 2.94 ERA over 477.2 innings, a span in which he's made his name as both an elite command artist and a top-tier ground ball magnet.

Whereas it's not uncommon to see slider-first pitchers anymore, Webb is baseball's foremost changeup-first pitcher. And why not? His has held hitters to a .224 average and has been the second-most valuable pitch in MLB.

Age: 32

2023 Stats: 25 GS, 150.1 IP, 136 H (16 HR), 195 K, 38 BB, 3.23 ERA

When Kevin Gausman broke out with the Giants back in 2020, it might have been written off as a fluke of the shortened schedule.

Three years later, Gausman has more than earned his proper credit by pitching to a 3.17 ERA over his last 576.2 innings. That's with 5.4 times as many strikeouts as walks, about 60 percent of which have come via the best splitter in the game.

Further, consistency is as much a defining trait for Gausman as for any other pitcher. The last time his ERA was over 4.00 was on April 14, 2022. That was 54 starts ago.

Age: 30

2023 Stats: 26 GS, 142.0 IP, 100 H (15 HR), 184 K, 80 BB, 2.73 ERA

Blake Snell began his Padres tenure with a pedestrian 4.20 ERA in 2021, and he even went into the 2022 All-Star break with a 5.22 ERA.

This feels like forever ago. The 2018 AL Cy Young Award winner's ERA in 40 starts since last year's break is 2.54, and even that fails to impress relative to the 1.48 ERA he's posted 17 outings since May 25 of this year.

The knock on Snell has been and still is that he's overly prone to walks, but that's fine so long as he remains borderline impossible to hit. As it bears a .058 average since May 25, it's indeed been close to literally impossible to hit his curveball lately.

Age: 28

2023 Stats: 27 GS, 168.0 IP, 144 H (16 HR), 179 K, 34 BB, 3.11 ERA

There's at least one thing that ties Snell and Zac Gallen together: like the former, the latter also has exactly a 2.54 ERA dating back to the 2022 All-Star break.

A big difference is that Gallen has achieved this while pitching 38.1 more innings, which is partially related to another big difference between the two. Gallen simply doesn't waste pitches on walks, and especially not this year as he's issued 1.8 free passes per nine innings.

Gallen is also proving that even pitchers with 40th-percentile velocity can have overpowering fastballs. His four-seamer is indeed the most valuable pitch of 2023, a testament to the usefulness of owning the edges of the zone.

Age: 32

2023 Stats: 26 GS, 160.1 IP, 129 H (17 HR), 170 K, 43 BB, 3.03 ERA

By all rights, Gerrit Cole should be taking a step back this season. He's lost 1 mph off his fastball and is one of the year's biggest strikeout rate decliners relative to 2022.

In actuality, it was only amid his last start that his ERA climbed over 3.00 for the first time all year. And it's still good enough to lead the American League, which he likewise leads in innings pitched.

Cole's sheer reliability is the other reason he's No. 1 on this list. Only he and Aaron Nola have pitched over 1,000 innings since 2018, and Cole has done so while maintaining a 3.00 ERA and striking out 5.2 as many batters as he's walked.

Put another way, he's a constant in an era of rising and falling aces.

Stats courtesy of Baseball Reference, FanGraphs and Baseball Savant.