In modern postseason baseball, when the best teams have multiple shutdown bullpen guys who can hit triple digits on the radar gun, how important is elite starting pitching? And more to the point, an ace? Or maybe two.
An ace has long been viewed as essential to a deep October run. Great pitchers get big outs, and none are bigger than in the postseason. Most in the baseball world agree: an ace can be the difference between a first-round exit and a World Series championship, but is that still the case?
For a term thrown around so often, it remains ambiguous without a universally accepted statistical definition. What teams ask of top starters has changed completely over the last 20-plus years. Racking up innings and finishing games, once a hallmark of elite starting pitching, now feels very foreign.
As the sport keeps evolving, what makes an ace today, and are they still imperative for deep playoff runs? To determine whether that sentiment is true, I first need to define what an ace is; without that, it is as subjective as the term itself.
Then, using that definition, I look at the last 10 World Series winners and losers.
I divided ace into two categories: an established ace and an ace-caliber season.
An ace-caliber season has to meet three benchmarks: 150-plus innings, a 130 ERA+ or higher, and over a 4.0 WAR. This is a working definition; it is not absolute whatsoever.
How did I arrive at these criteria?
150 innings is a big enough sample size. Not accounting for off days, injuries, etc., in a traditional five-man rotation, each pitcher roughly averages 32.4 starts per season. Moreover, last season starters averaged about 5.2 innings per outing. If we factor in the possibility of missing three to four starts and multiply that by average innings per outing, the result is about 145.6-150.8 innings.
ERA+ reflects a pitcher’s season much more accurately than ERA. A mark above 130 represents run prevention roughly 30% better than league average, adjusted for the ballpark. Last season, only 13 pitchers met this mark. It’s an exclusive enough benchmark while being attainable.
The 4-WAR mark reflects a high amount of value contributed; last season, only 17 pitchers reached this figure. Again, this threshold is restrictive enough yet surpassed quite often.
Established aces are pitchers who have had an ace-caliber season multiple years in a row, with Cy Young Awards and even MVPs. You already know the names: Scherzer, Verlander, Cole, etc.
These are not set criteria. I’m not going to pretend that a season where two of the three criteria are met automatically denies you an ace-caliber season, or having such a season every three years negates your ace status.
After the season Dylan Cease is having, most would consider him an established ace, right? The veteran right-hander has never met the threshold in consecutive seasons. In the previous three seasons leading up to 2026, Cease had a below-league-average ERA+ twice. Players fluctuate above and below the threshold often. Still, the former Cy Young runner-up is considered an ace by most.
With the definition established, let’s now apply that framework to October baseball.
Of the last 10 World Series champions, nine had an established ace or a pitcher who had an ace-caliber season. Conversely, seven of the last 10 World Series runners-up had either an established ace or a pitcher with an ace-caliber season. Put simply, over the last decade, one team won without an ace, and seven runners-up had an ace and did not.
In some cases, an ace is everything they’re advertised to be. For the World Series-winning 2019 Washington Nationals and 2017 Houston Astros, Stephen Strasburg and Justin Verlander were exactly that.
After posting an ace-caliber season, Strasburg was even better in the playoffs. Throughout the postseason, he pitched to a 1.98 ERA and posted a 2.51 ERA in the World Series. In Game 6 of the championship, facing elimination, he nearly pitched a complete game, going 8.1 IP and allowing only two ER. When the lights were brightest and the game was on the line, the right-hander stepped up and helped the team win a World Series title.
For the Astros, trading for Tigers ace Justin Verlander at the 2017 deadline was all they were hoping for. In his new threads, the future Hall of Famer recorded a 0.56 ERA across 16 ALCS innings. In Game 2, he pitched a one-run complete game, and in Game 6, he pitched seven shutout innings to force a Game 7, which they would eventually win. Although he didn’t pitch as well in the World Series, he played a major role in helping the franchise capture its first world title.
Under October’s spotlight, when the moments are the biggest, the postseason has its own way of producing aces. For the 2023 Rangers, that was Nathan Eovaldi. Throughout his 15-year career, the veteran right-hander has seemed to save his best for the postseason.
In 2023, he pitched to an above-average, but not quite ace-caliber, 118 ERA+ in just 144 innings. Texas already had an ace in Jordan Montgomery, but come October, he was not alone.
When the Fall Classic came around, Eovaldi turned into a different pitcher. In six postseason starts, he posted a 2.95 ERA in 36.2 IP, and the Rangers went 6-0 in his starts. Even more impressive, he earned three series-clinching wins: one in the wild card, one in the ALDS, and one to clinch the World Series title, allowing one earned run or fewer in each.
Reggie Jackson was “Mr. October”; Derek Jeter was “Mr. November”; maybe it’s time we give Eovaldi his own moniker: “Nate-tober.”
This now begs the question: Can you win a World Series without an ace? The 2024 Dodgers proved it is possible.
Injuries gutted the Dodgers rotation; entering October, the club had only three healthy traditional starters: Jack Flaherty, Yoshinobu Yamamoto and Walker Buehler. Individually, none reached more than 23 postseason innings, and together they recorded only 55.2 innings. To compensate for a thin starting staff, the Dodgers spread out innings throughout their bullpen.
During the postseason, their starters threw only 42% of their postseason innings, the lowest percentage for a World Series champion in MLB history. In four of the 16 playoff games, they did not use a traditional starter and threw bullpen games. Game 4 of the NLDS, facing elimination — a day almost all Padres would rather forget — eight different Dodgers pitchers combined to shut out San Diego.
Without an ace or a pitching staff, for that matter, the Dodgers still claimed a World Series title.
They are not necessary to win in October, and having one doesn’t guarantee a championship either. Still, they are extremely valuable; nine of the last 10 World Series champions had an established ace or a pitcher with an ace-caliber season. Even then, they can only pitch so many innings. The rest falls on the offense and bullpen.
Teams can win a championship in multiple ways. Some are won on the strength of an ace; others have a pitcher emerge in October; others share the responsibility. Needless to say, all teams need great pitching in October.
As the role of pitchers continues to evolve, what it means to be an ace does too. Even so, for as long as baseball has been around, it has always been and still is about giving your team the best chance to win.