It's truly impressive how much expectations can change how a player's career and numbers are perceived.
Maybe that's not quite the right way to explain Griffin Jax, but consider this: in his rookie season, he threw 82.0 innings and had a 6.37 ERA, 7.1 K/9, 3.2 BB/9 and an astonishing 2.5 HR/9 allowed. He averaged 92.7 mph on his fastball that season.
In the three accompanying years since, Jax has thrown 72.1, 65.1 and 71.0 innings, respectively. On the surface, you'd say he's thrown very similar innings totals every year of his career. You wouldn't necessarily be wrong.
And obviously part of Jax's improvement over the years can be chalked up to simple big-league experience. Many players are hit hard the first time around, only to improve while remaining in their previous role.
Jose Berrios is a high-profile example of this. In his rookie season, he posted an 8.02 ERA in 14 starts. Over the next three full seasons he spent with the Twins, by comparison, he had a 3.80 ERA and looked like a drastically different pitcher.
But even given Jax credit for time served doesn't entirely explain the leap he's taken.
That leap is the "middling starter-to-reliever" special. The Twins have seen this many times over the years, including Eddie Guardado, LaTroy Hawkins, Glen Perkins and even Liam Hendriks, though they didn't get to see the fruits of Hendriks' labors as his breakout as a reliever happened elsewhere.
Jax has only gotten better year-over-year since transitioning to relief full-time, and that applies in myriad ways. His fWAR has gone from 0.9 to 1.2 to 2.6 over this three-season run. His average fastball velocity has leapt from 95.4 mph in his first season as a reliever to 97.1 last season.
And his strikeout rate, which was 9.71 per nine innings in 2022, jumped to a stunning 12.04 in 2024.
Jax's ERA of 2.03 was nearly two runs lower than in 2023 (3.86), and despite that, at least one peripheral statistic suggests he pitched even better than this mark indicated (his FIP was 1.94).
The transformation has been nothing short of incredible. Jax didn't strike anyone out, didn't have very good command, gave up a ton of home runs and perhaps most interestingly, at least to me, did not induce grounders in any way, shape or form as a starter (31.9 percent, against an MLB average that's usually in the 45.0 percent range).
As a reliever, Jax has posted groundball rates in excess of 50.0 percent in each of the last two seasons. That, combined with insane strikeout and walk (1.90 BB/9 last season) marks line up as the Holy Trinity in pitching.
Get strikeouts. Limit walks. Keep the ball on the ground.
That's a three-step plan that'll get pitchers wherever they want to be. Grounders can't leave the ballpark. They almost never go for extra-base hits. For a reliever who comes into a clean inning far more often than not, this is a tremendous combination.
And beyond that, Jax has the swing-and-miss stuff to put out a fire if he comes in with runners on in a dicey situation.
But the goal of this piece is to determine if Jax will be better or worse in 2025 than he was in 2024, and to be honest....is it even possible to be better?
There are better ways to evaluate relievers than fWAR, but indulge me for a moment: there have been only three reliever seasons that have resulted in a higher fWAR from a reliever in Twins history (post-Washington):
- 1970 Tom Hall: 4.1 (he started 11 games and threw 155.1 innings)
- 2006 Joe Nathan: 3.1 (credit where due, he was insanely good)
- 2004 Joe Nathan: 3.0 (not bad for a guy who was handed the job after being in the Francisco Liriano-A.J. Pierzynski trade)
- 2003 LaTroy Hawkins: 2.6 (same as Jax last season, and this was who Nathan was brought in to replace...big shoes, huh?)
It's unfair to expect Jax to find another gear this season, but here's a thought: he could technically improve by taking over the closer's role in some way, shape or form and holding onto it for the rest of the season.
That's a pretty narrow path. We'd obviously never wish ill upon Jhoan Duran.
But short of this extremely unlikely scenario, it's hard to imagine a way Griffin Jax is even better in 2025 than he was in 2024.
And that's by no means a bad thing. Jax was nails in 2024.