Which Team in the AL West Has the Best Ace for 2025?
The AL West has some of the best starting pitching in all of baseball; but which team has the best ace leading their staff?
The American League is absolutely jam-packed with pitching talent right now, and so much of that is coming from the AL West, where many of the game’s best arms are being stockpiled.
Over in the AL East, the big bad New York Yankees have Gerrit Cole (who is now out for the year after a Tommy John surgery) and Max Fried, while the Boston Red Sox and Tampa Bay Rays have multiple true aces in their pitching rotations.
But for every top-end pitcher on a non-AL West team, a team in the West has two more. The Seattle Mariners have five or even six starters that could earn their way to the All-Star Game this year and emerge as the leader of the rotation, while the Texas Rangers have one of the best starting pitchers we’ve seen in recent memory – perhaps ever – leading theirs.
Even the Los Angeles Angels and Athletics, who are widely expected to be the fourth- and fifth-place teams in the division in 2025, have respectable hurlers atop their rotations and should not be immediately written off.
As part of a series of posts we’re putting out here at Just Baseball, let’s take a closer look at the staff aces over in the AL West and rank them. It’s not an easy task – especially once you get towards the top of the list – but it must be done.
Ranking the Aces of the AL West in 2025
5. Athletics – Luis Severino
2024 Stats
| GS | IP | W-L | ERA | FIP | K/9 | BB/9 |
|---|---|---|---|---|---|---|
| 31 | 182 | 11-7 | 3.91 | 4.21 | 8.0 | 3.0 |
It’s easy to look at the Athletics and feel unimpressed by their 69-win showing in 2024. However, they were widely expected to be the AL West’s cellar dwellers and they showed some legitimate signs of life down the stretch.
The A’s worked hard to upgrade their starting rotation this past winter, and there’s no doubt that it’s going to be an improved unit in 2025. Jeffrey Springs was easily the organization’s biggest trade acquisition, and he could’ve been tabbed for the Opening Day start without making anyone doing a double take.
A long-time relief pitcher who seamlessly transitioned from the ‘pen to the rotation, Springs has dealt with a myriad of injuries over the past few years, but when he’s on, he’s electric. The southpaw has a combined 2.44 ERA and 3.10 FIP dating back to 2022 when he first began his transition to starting.
JP Sears, Mitch Spence, and Osvaldo Bido are the three holdovers from last year’s roster that project to open the upcoming campaign in the A’s rotation. Each of them have their own respective cases to be the club’s season-opening starter, but none of them are quite at “staff ace” status yet.
But it’s got to be Severino, who’s coming off of one hell of a bounce-back showing with the Mets, who will lead this young and unproven rotation. Severino, 31, made 30+ starts last year for the first time since 2018 and was one of the Mets’ best pitchers. He was properly rewarded for this performance by bringing home the largest free agent contract in A’s history.
Having Severino join this team coming off of such a strong season is huge for the A’s, who are counting on a continued surge up the standings in 2025. He finished 15th in the majors in innings pitched last year, which is such a massive accomplishment in itself for a pitcher who has struggled so mightily with injuries.
4. Los Angeles Angels – Yusei Kikuchi
2024 Stats
| GS | IP | W-L | ERA | FIP | K/9 | BB/9 |
|---|---|---|---|---|---|---|
| 32 | 175.2 | 9-10 | 4.05 | 3.46 | 10.6 | 2.3 |
Even if the Angels are likely going to finish 2025 below the A’s in the standings, the Halos have the edge in ace ranking. Kikuchi, who’s closing in on his 34th birthday, had a turnaround for the ages on the Houston Astros last year and rode his 60-inning showing there right out of the last spot in our ranking.
Kikuchi, a six-year veteran, had spent the previous two-and-a-half years on the Toronto Blue Jays, functioning is a frustratingly inconsistent arm who was a lock to make every single scheduled start of the season but nothing more. He looked “just okay” leading up to the 2024 deadline, but Toronto was still able to flip him to Houston for a significant package of young players.
Right when he landed on the Astros, Kikuchi saw his game elevate to a level it never has before. He promptly struck out 11 batters in his first start as an Astro and went on to punch out seven or more batters five more times. In his 10 starts in Houston, the left-hander never went less than 5.1 innings and never allowed more than four earned runs in a single start.
So much of his newfound ability to dominate the opposition comes from a few tweaks to his arsenal. On the Astros, he began to rely on his offspeed pitches more, including a heavy reliance on his changeup and slider that wound up paying major dividends for all involved.
Now, Kikuchi will lead the Angels’ pitching staff as he continues his quest to make starts for every team in the AL West. He would’ve easily been their best pitcher last year and the projections have him being just that in the coming season too.
That doesn’t mean this is a rotation completely devoid of talent though. Jose Soriano and Tyler Anderson, who will likely open the year in the two- and three-spots in the Angels’ rotation, both turned in respectable campaigns and there’s a great chance one of them would’ve been the club’s Opening Day starter if it weren’t for Kikuchi’s acquisition.
Kyle Hendricks was another offseason addition for the Angels, but the odds of him making it to the end of the year with a job feel… well, low.
Don’t forget about Reid Detmers either, who needs a bounce-back campaign in the worst way. We’ve seen some legitimate glimpses of promise from him since he debuted, but the 2025 season will go a long way to determining if he’s going to stick around or not on this team.
3. Houston Astros – Framber Valdez
2024 Stats
| GS | IP | W-L | ERA | FIP | K/9 | BB/9 |
|---|---|---|---|---|---|---|
| 28 | 176.1 | 15-7 | 2.91 | 3.25 | 8.6 | 2.8 |
No disrespect to Severino or Kikuchi, but this is where our list really takes off. The first two entrants on our ranking are solid pitchers in their own rights, but they’ve got nothing on the three Cy Young-caliber arms we’ve got coming up next.
The fact that Valdez, one of baseball’s best left-handed pitchers, is third in the division says so much about the pure talent we’re working with here.
Last year, the seven-year veteran posted what was easily the best of his big league career – at least bWAR-wise. Coming in at 4.4 to round out his 28-start showing, he was a full Win above his previous career-high from 2022 when he finished fifth in the Cy Young voting.
Valdez is consistent and has been a run-prevention machine all throughout his career. Once he established a firm hold on a rotation spot in Houston around 2021, he never looked back.
On the full-season leaderboards, the southpaw wound up second in the AL in HR/9, ninth in strand rate, first in groundball percentage, and then third in both ERA and FIP. Basically any way you slice it, he was one of the best starters in the game last year and he’s the obvious choice to be the Astros’ staff ace in the coming season.
While the Astros’ rotation doesn’t carry the same amount of weight it did a few years ago, there are still some solid reinforcements behind Valdez. Hunter Brown is an ace-in-the-making and is five years younger than Valdez. It has felt for a while now that Brown is on the cusp of greatness and it seems that as of right now, he’s the club’s long-term ace.
The only thing keeping Brown from that label right now is the fact that last year was his first successful one in the big leagues. He made 30 starts and finished the year with a 3.49 ERA and 3.58 FIP and improved his numbers in every single way from the year prior. A strong 2025 showing from him would go a very, very long way.
Ronel Blanco and Spencer Arrighetti are two of the stronger No. 3 and 4 starters in the league, especially if they can continue to build off of the performances they had last year.
Blanco, 31, threw a no-hitter last year and finished his season with a 2.80 ERA and a H/9 that led all of baseball. He’s a late bloomer, but he handled a full season’s worth of starts very well. Heck, he struck out two more batters per nine innings in the second-half of the year, so if he anything he upped his game as the summer months marched on. Similarly to Brown, It’ll be interesting to see how Blanco performs in year two.
The 25-year-old Arrighetti struck out 10.6 batters per nine innings but at times showed a proneness to the free pass. He’s still young and very inexperienced, but he showed more than enough to warrant a spot in the Astros’ Opening Day rotation. He’s far from being an ace-caliber pitcher, but his career is off to a damn good start.
2. Seattle Mariners – Logan Gilbert
2024 Stats
| GS | IP | W-L | ERA | FIP | K/9 | BB/9 |
|---|---|---|---|---|---|---|
| 33 | 208.2 | 9-12 | 3.23 | 3.27 | 9.5 | 1.6 |
Availability is the name of the game in modern baseball, and it’s never been more valuable to take the ball every fifth day and go deep into ballgames all at the same time. Last year, Gilbert led the majors in starts and innings pitched, while turning in the game’s best WHIP for good measure, too.
The right-hander hasn’t made less than 32 starts in each of the past three years and has topped the 185-inning mark in each of them. He’s extremely stingy when it comes to allowing hitters to reach bae and did more than enough to stand out in a staff filled with ace-like pitchers.
Gilbert, 27, was an All-Star last year and wound up sixth in the Cy Young voting. A look at the leaderboards will show you that he finished third in the AL in BB/9, second in BABIP, ninth in ERA, sixth in FIP and fifth in fWAR. There’s no statistic that will tell you he’s anything less than a true ace.
In George Kirby, Bryce Miller, and Bryan Woo, the Mariners have assembled a staff of budding stars to line up alongside Gilbert. None of them have reached their 28th birthday yet and all bring ace-like talent to the table.
Unfortunately, Kirby is going to miss Opening Day as he works through a shoulder issue. As he recently told Ryan Divish of The Seattle Times, a mid–April return looks to be the likeliest outcome.
Most of Seattle’s rotation is highlighted by the impressive amount of young talent they’ve accrued, but what about the old timer Luis Castillo? The 32-year-old took a slight step back last year, but remained a positive contributor and, like Gilbert, was good for 30 starts.
Castillo, an eight-year veteran, will open the season as the Mariners’ No. 2 starter, but he’s no stranger to being an Opening Day starter. He’s a multi-time All-Star who can reach the 200-strikeout mark in any given year and is going to be an extremely crucial part of this quintet – especially if Kirby happens to hit a snag in his recovery.
1. Texas Rangers – Jacob deGrom
2024 Stats
| GS | IP | W-L | ERA | FIP | K/9 | BB/9 |
|---|---|---|---|---|---|---|
| 3 | 10.2 | 0-0 | 1.69 | 2.32 | 11.8 | 0.8 |
Look, I completely understand that a pitcher who has made 20 starts since 2021 doesn’t exactly feel like the best ace in the AL West. It’s also fair to call Nathan Eovaldi the Rangers’ ace. My only argument is that this is Jacob freakin’ deGrom we’re talking about. The same Jacob deGrom who has routinely been one of the very best pitchers in all of baseball when he’s on.
Simply put, there’s nobody more masterful at his craft than deGrom is – when he’s healthy. All signs are pointing to him being up to speed to kick off 2025, so how can you reasonably go with anybody else other than the surefire Hall of Famer who is still dominant whenever he takes the mound?
deGrom may be turning 37 in June, but he remains absolutely lethal whenever he’s “on.” The right-hander has only made nine starts dating back to 2023, but he’s allowed a total of three earned runs across 41 innings, which is good for a 2.41 ERA and 1.74 FIP. Oh, and he’s also punched out over 13 batters per nine during that stretch.
Dating back to 2018, deGrom is first in all of baseball ERA (2.07) and FIP (2.12), second in K/9 (12.26), strand rate (81%), HR/9 (0.71), seventh in BB/9 (1.73). You don’t need me to continue to throw stats at you to prove that he’s ridiculous on the mound.
Like I said, as of right now, there’s nothing to suggest that deGrom isn’t healthy and gearing up for his first full season of starts since 2019. Based off of how utterly dominant he’s been in the games he has started over the past few years, how are you supposed to go with anybody else?
Rangers manager Bruce Bochy has already announced that Eovaldi is going to be the club’s Opening Day starter this year, with deGrom starting at the back of the rotation to build back up to a full season’s workload. Eovaldi will be the first Rangers pitcher to earn consecutive Opening Day starts since Kevin Millwood (2006-2009), and is deserving of the honor. Even so, it feels like the top spot in the rotation is deGrom’s for the taking if he can prove that he’s got health on his side.
Still, Eovaldi has been rock-solid for years now. Since 2021, he’s made a pair of All-Star Games, posted four straight mid-3.00 ERAs and even earned some Cy Young consideration. The Rangers had an easy decision on their hands in whether or not to re-sign him this past offseason.
Eovaldi’s re-addition to the rotation becomes more important once you factor in Tyler Mahle’s questionable durability, Jack Leiter and Kumar Rocker’s uncertainties as they transition to a big league role for the first time, and the current injury status of Cody Bradford and Jon Gray.
The Rangers had such a busy offseason but their starting rotation is already beginning to thin out before Opening Day even gets here. Leiter and Rocker have both been highly-touted prospects over the years, but we’re still waiting to see what the two young guns can do in a full season worth of starts in the big leagues. If they prove they have what it takes to stick, great. If they struggle, then you start to rely too heavily on Patrick Corbin to anchor your rotation, and that’s when you know you’ve got trouble.
Written by
Eric Treuden (troy-din) has covered baseball for years for multiple different outlets including FanSided, Yardbarker, and Wisconsin Sports Heroics. He recently was the editor for Jays…