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Alex Reyes: A Tale of Two Halves

Yes, the walk rate was bad. But that’s not the only issue Reyes faced in 2021.

MLB: Wildcard-St. Louis Cardinals at Los Angeles Dodgers Robert Hanashiro-USA TODAY Sports

Earlier this week, VEB’s Blake Newberry took a look at Alex Reyes’ potential to contribute as a member of the rotation in 2022. It provides a really good overview of Reyes’ 2021 season and a great evaluation of where Reyes will likely fit into next year’s pitching staff. If you haven’t read it yet, I highly recommend you do so. This piece will touch on some of those points from Blake’s article (it’s really hard not to mention that walk rate), but the focus will be more retrospective to Reyes’ 2021 season.

As mentioned, Reyes’ walk rate in 2021 was abysmal at 16.4%. As he put together a record-setting streak of saves, some who watched dreaded the potential for the other shoe to drop, and in the second half, it did. Reyes’ walk rate of 18.2% in the first half of 2021 was already a recipe for disaster, but he offset it with a strikeout rate of 30.7%. He also limited damage from the long ball, giving up just 0.44 HR/9. This resulted in a 3.51 FIP in the first half of the season, which Reyes outperformed to the tune of a 1.52 ERA.

As probably all of the readers here know, Reyes’ second half of the season did not go nearly as well. Though his second-half walk rate dropped to 14.2%, his strikeout rate also dropped slightly to 29.1%. If that were the only difference between the two halves, Reyes might have remained the closer for the Cardinals going deeper into the season, frustrating walk rate and all. But his HR/9 ballooned to 2.03, and opponents’ slugging percentage jumped from .210 in the first half to .395 in the second. Those numbers are disastrous for a pitcher that has a high tendency to give free passes. It all added up to a 5.59 FIP and a 5.52 ERA.

The answer to why Reyes’ second half went so wrong is pretty straightforward at the surface level: He got hit really hard when guys managed to make contact. Digging a little deeper, however, there are some interesting differences in both Reyes’ pitching approaches between the two halves of the season, as well as his pitch execution.

Alex Reyes has five pitches: a four-seam fastball, sinker, slider, curveball, and changeup. Coming out of the bullpen, he’s relied pretty heavily on the fastball, sinker, and slider, which checks out when looking at his pitch usage in the first half of 2021.

1st Half pitch usage and velocities, created using

No surprises so far. The following is the same graph, but for the second half of 2021:

2nd Half pitch usage and velocities, created using

Reyes increased the percentage of sliders he threw from about 26.1% of his pitches in the first half to about 30.6%. He also increased the percentage of changeups he threw, and the increases in the frequency of these pitches certainly seem to come at the expense of Reyes’ fastballs. (It should be noted that Reyes threw about ten fewer innings in the second half of 2021 than he did in the first, so with more comparable sample sizes these distributions may have evened out a little more.) The slider is a great pitch for Reyes, and it makes sense that he would lean on that pitch heavily as the season progressed. He didn’t get the results he hoped for, however. The following graphs show the locations of batted sliders as well as their exit velocities in each half of the season:

1st Half locations and exit velocities for batted sliders, created using
2nd Half locations and exit velocities for batted sliders, created using

Finally, these heatmaps represent opponents’ slugging percentage per pitch (SLG/P) for Reyes’ sliders in each half of Reyes’ 2021 season:

1st Half Opp. SLG/P for Alex Reyes’ sliders, compiled using
2nd Half Opp. SLG/P for Alex Reyes’ sliders, compiled using

Reyes relied on his slider disproportionately in the second half, but he simply couldn’t seem to execute the pitch. His second-half sliders often sat up in the zone or just off the plate on his arm side, and those pitches were absolutely hammered by opposing hitters. The subpar results from his sliders may have been part of the reason that Reyes threw more changeups in the second half as well. There may be some evidence to suggest that location wasn’t the only problem with the pitch. The Baseball Savant Data does imply that there was slightly less horizontal movement on his sliders in general in the second half of the season. His first-half sliders typically maxed out at about fifteen to sixteen inches of break, but his second-half sliders broke no more than twelve to thirteen inches, suggesting that the pitch itself wasn’t as sharp as it was in the early parts of the 2021 campaign. However, the locations of the pitches when they hit the zone are spots where no pitcher wants to make a living with breaking balls, and it’s very likely the bigger of the two factors here.

Somewhat ironically, we’ve returned to a discussion regarding Reyes’ control. Even when his slider isn’t at its sharpest, it’s still a pretty filthy pitch, and one can hardly blame Reyes for leaning on it heavily in the second half. But in 2021, he simply lacked the ability to hit the strike zone, and when he did hit the zone with his sliders, he lacked the command to put the ball on target. If the uptick in his changeup usage was the result of Reyes’ or Yadier Molina’s awareness of this issue, it’s something he’ll hopefully put more time into in the offseason. And if he truly wants to be considered as a rotation piece in 2022, he’s going to need to improve both his control and command to cut down on walks and to better locate his pitches in the zone.