The statistical absurdity – and brilliance – of Snell's '23 season

September 19th, 2023

When's Mike Petriello examined the complicated 2023 NL Cy Young Award race, it was the Padres' who threw the biggest wrench in how to evaluate this year's group of NL pitchers.

The 30-year-old lefty is wrapping up one of the most bizarrely dominant and statistically extreme seasons by any pitcher in MLB history. On one hand, Snell leads the Majors with a 2.43 ERA, a .186 opponents' batting average and a .597 OPS against, and he has 217 strikeouts in 167 innings, which is more than enough to qualify as one of the game's best pitchers. At the same time, Snell is also the MLB leader with 93 walks and could become the first pitcher since 2012 with 100-plus walks in a season.

Nobody doubts that Snell has been an extremely effective pitcher this season and will warrant conversation for the best NL pitcher. What is in question is how good he's actually been and how Snell has been able to outperform every indicator of what his ERA should be.

Heading into Snell’s next start on Tuesday night against the Rockies, here’s a look at just how unusual his 2023 season has been and how he has been able to pull it off.

The unicorn season

There are plenty of ways to show how unique Snell's 2023 season has been, but these are some of the standout metrics:

  • Snell is looking to become the first AL/NL pitcher since 1913 -- when earned runs became official in both leagues -- to lead the Majors in both ERA and walks. Snell leads in ERA by 30 points over (2.73) and has 12 more walks than (81).
  • Snell has a whopping 13.4% walk rate, making this one of 173 seasons in MLB history in which a pitcher had a walk rate above 13% in 150 or more innings. Snell’s 169 ERA+ would be the highest of all those seasons, besting 's 162 ERA+ in the 1942 season.
  • If Snell walks seven more batters the rest of the season, he'd become the second pitcher ever -- and first since in 1966 -- with 200 or more strikeouts and 100-plus walks across fewer than 200 innings in a season.
  • If he wins the Cy Young Award, Snell would become the first pitcher since in 1959 to lead the Majors in walks while winning the award.

The common denominator in Snell's funky season is the walk total. It's just extremely difficult to allow that many free passes and still find this level of success. Even some of the extreme examples similar to Snell -- like and -- never led the Majors in both ERA and walks in the same season. For Snell, those walks are just a part of his profile, which has seemingly been embraced by the lefty and the Padres this year.

In a recent story from's Padres beat reporter, AJ Cassavell, Snell and the Padres all but confirmed this idea that his high walks total is OK.

"I've got a guy here that has stuff. The message is: Go get outs. It's not: Don't walk people," Padres pitching coach Ruben Niebla told Cassavell. "Walks are part of the game, and you have the stuff to be able to pitch through walks."

Snell seconded this notion and even talked about a belief in "good walks" vs. "bad walks." Rather than give in to hitters and throw hittable pitches, Snell is comfortable walking a batter and working his way out of trouble. While this isn't a sound game plan for most pitchers, Snell isn't exactly like most pitchers.

How to win with walks

Snell has made this high-strikeout, high-walk profile work because he's been one of the most unhittable pitchers this season. In the pitch-tracking era (since 2008), only three starters have generated a higher single-season whiff rate -- the percentage of swings that result in a miss -- in a single season than Snell this year.

Highest whiff rate in a single season, SP, pitch-tracking era
Min. 150 innings

1. (ATL), 2023: 39.6%
2-T. (MIL), 2021: 37.3%
2-T. (HOU), 2019: 37.3%
4. Blake Snell (SD), 2023: 36.6%
5. (CIN), 2019: 35.7%

Part of his ability to miss bats is due to the fact that he's a 6-foot-4 lefty who throws a mid-90's fastball. It's the trio of secondary pitches, though, that does the heavy lifting in generating boatloads of whiffs. Like many other pitchers of his era, Snell has opted to use his best pitches more often. For the first time in his career, his fastball rate dipped under 50% this season, which has led to Snell throwing his elite secondary offerings more than half of the time.

Snell's curveball has been his most utilized secondary pitch (18.9%) for the first time since his 2018 AL Cy Young Award-winning season and has been one of baseball's best pitches. It's the third-best pitch by whiff rate (54.9%) among starting pitchers and the fourth-most valuable breaking ball or offspeed pitch according to run value -- the run impact of an event based on the runners on base, outs, ball and strike count. In 154 plate appearances ending on the curve, opposing hitters have just 12 hits and a .150 SLG.

As if a mid-90's heater and elite curveball weren't enough, Snell also mixes in a spectacular changeup and slider. Both pitches are not too far behind in terms of bat-missing ability and overall dominance. Snell's changeup has the ninth-highest whiff rate (47.7%) among individual pitch types (min. 150 swings) and is second only to 's changeup. His slider, meanwhile, has a 53.6% whiff rate that trails only four pitches, including his own curveball.

When you combine the overall excellence of his non-fastballs, Snell is producing one of the most dominant seasons on breaking balls and offspeed pitches by a starting pitcher in recent memory. He has a combined 51.1% whiff rate on his non-fastballs, the second-best single-season rate by a pitcher behind only Strider, who has a 55.3% whiff rate on his slider and changeup this year.

When you're simply preventing hitters from making contact against you, that goes a long way toward making this profile work.

Pitching well when it matters

This is where Snell's season gets even more interesting. Based on many ERA indicators -- whether it's expected ERA (3.86), FIP (3.53) or expected FIP (3.65) -- Snell is outperforming his underlying numbers by over a full run. That's what you'd expect from a guy who's walking 13.4% of the hitters he's facing. Unsurprisingly, Snell's high-walk, high-whiff profile and his minuscule ERA is also backed by incredible numbers with runners on base and in scoring position.

When runners get on base, Snell strands them 85.9% of the time -- the 12th-best mark by a starting pitcher in a single season (min. 150 innings) since 1901. What works in Snell's favor is many of the seasons ahead of him are some of the best pitching performances in MLB history, such as 's 1968 season, circa 1985 and 's 2000 season. Also ahead of him? Snell's own Cy Young Award-winning season in 2018 (88%).

That last point is especially important in this context. One might look at Snell's .500 OPS allowed with runners in scoring position this year -- fourth best among starters -- and simply write it off as luck. Except that Snell was even better with RISP in 2018. His .374 OPS allowed with RISP in 2018 is the third-lowest single-season mark by a starter dating back to 1901. This raises the question: Is this a skill or random noise?

It might be a little bit of both. Snell owns a career .642 OPS allowed with RISP, which ranks 47th all time among starters (min. 100 starts) who've faced at least 500 batters with RISP. He also has a .192 expected BA with RISP this season, giving him further support that he really is pitching better in these situations.

At the same time, half of Snell's eight MLB seasons have seen him allow an OPS north of .700 with RISP. Situational pitching -- and the small samples that come with it -- tend to have wild year-to-year fluctuation. Good pitchers like Snell, however, tend to find themselves pitching out of jams.

It's also notable that Snell has been the benefactor of great defense behind him this season. When it comes to good batted-ball luck, having strong defense tends to put more good luck on your side. While the Padres have underperformed this season, their defense certainly has not. Led by defensive stalwarts , , and , San Diego's defense ranks sixth or better in Outs Above Average (+26), Defensive Runs Saved (+37) and Ultimate Zone Rating (+24). They've been especially good behind Snell, providing +7 OAA when he's on the mound, which tied for the 12th-most by any defense for an individual pitcher.

As is the case for most great seasons, there's some combination of factors that need to come together at the right time. Mostly, that’s the player performing at his best, but with that also comes at least some good fortune. Snell’s 2023 is no different.

Whatever you think of it, one thing is for sure: Snell is putting together a season unlike any we’ve ever seen. And when all is said and done, it just might result in his second career Cy Young Award.