Astros’ starting pitchers allowing hard hit balls
If you are a pitcher, hard hit batted balls usually are not a good thing. I think we all know that intuitively. Let’s take a look at hard hit balls and their impact on some of the pitchers in the Astros’ rotation.
What brought this to my attention? As I reviewed pitcher leaderboards at Fangraphs, I noticed that Framber Valdez is allowing a lot of hard contact, although he is among the league leaders in ERA.
Among qualified starting pitchers, Framber Valdez allows the highest average exit velocity in the majors (91.8 mph). Interestingly, Hunter Brown allows the 10th highest average exit velocity (90.6 mph) in the majors. Framber Valdez and Hunter Brown are tied at 9th in average hard hit ball rate (percent of batted balls with EV over 95 mph). Yet Valdez is top five in ERA (2.94). Hunter Brown doesn’t fare as well in terms of ERA (4.19). It’s worth noting that, if Brandon Bielak had enough innings to qualify for the leaderboard, he would have the second highest hard hit rate in the majors.
What does pitcher exit velocity say about pitcher skill? That’s a question which is up for debate. A fangraphs article found that pitcher exit velocity is correlated with FIP, which suggests that pitcher skill affects the exit velocity allowed. A Five Thirty Eight article found that hitters are most responsible for exit velocity but that the pitchers’ contribution is not negligible with about a 20% responsibility for suppressing exit velocity. The article notes that pitchers can reduce hard hit balls by 20% through locating pitches and controlling the count.
The problem with equating exit velocity with pitcher skill is that there are so many factors mediating the impact of exit velocity on pitching results. One of the most important elements is ground ball rate, since hard hit ground balls are less likely than hard hit fly balls to lead to extra bases.
Furthermore, ground ball pitchers produce more double plays. Both Valdez and Brown are ground ball pitchers, which should limit the impact of exit velocity. For example, Valdez has the third lowest average launch angle in baseball (3.8), which should curb home run tendencies.
On the other hand, Cristian Javier has the second highest average highest launch angle in baseball (23.5). Although his hard hit rate is middle of the road, the launch angle may cause more risk from hard hit balls.
Another mediating factor is team defense and how well the defense converted hard hit balls into outs. There is both skill (on the part of fielders) and luck (such as “at ‘em” balls) involved in this factor. The impact of this factor may be revealed by comparing actual ERA to expected ERA (x-ERA). The x-ERA takes into account the probability that a ball would be caught by an average fielder. For Valdez, the actual ERA is over 1 run lower than x-ERA. For Bielak the actual ERA is almost 2 runs lower than x-ERA. For Brown, the actual ERA is 0.25 runs lower than x-ERA.
The pitcher’s ability to strike out batters and control walks also play a role in mitigating the impact of exit velocity. The best way to control exit velocity is to avoid contact, hence striking out the batter. Too many walks puts runners on base and provides a higher chance that exit velocity can drive in runs. For example, Brandon Bielak’s combination of a low strike out rate (7.11%), a high walk rate (3.88%), and high exit velocity should make one skeptical of his ability to maintain his good 3.62 ERA, going forward.
Valdez and Brown have almost the same ground ball rate and hard hit ball rate, yet Framber’s ERA is lower than Brown’s (2.94 vs. 4.19). One explanation may lie with Brown’s HR/fly ball rate. (Brown at 17.9% vs. Valdez at 11.4%). In theory, Brown’s high HR/fly rate should regress toward league average over time. This theory is the basis for x-FIP which sets HR/fly ball rate equal to league average. Valdez’s x-FIP (2.99) is much closer to Brown’s x-FIP (3.17) than the ERA difference would indicate.
Valdez’s league leading average exit velocity may be cause for some minor concern, but it doesn’t necessarily foretell a major increase in future runs allowed. Framber’s 3.97 x-ERA may indicate some risk of regression going forward. However, countering that, his FIP is pretty much in line with his ERA.
The area to keep an eye on in the future is Valdez’s ground ball rate. Valdez’s pitching this year reflects a number of changes which produce mixed effects. His velocity has increased, as has his strike out rate. On the other hand, higher velocity on his sinker may produce less sink. And his ground ball rate has declined from 67% in 2022 to a current 54%. Seemingly, Framber has managed this mix of results without any negative effects on his ERA. But if his ground ball rate continues to decline, it’s possible that the high exit velocity could have a more significant effect.
The Astros’ broadcast last night made the point that the Astros’ 44 unearned runs is the highest in the majors, despite the team’s middle of the pack ranking in errors. It is interesting that the team’s unearned runs seem to have the greatest impact on pitchers with a high hard hit ball rate. Bielak and Pressly are 1 and 2 in hard hit rate, and also have the most unearned runs (6). Valdez and Brown are 3 and 4 in hard hit rate and have the next highest number of unearned runs (Valdez 5; Brown 4). This may or may not mean anything. But it is possible that higher exit velocities tend to lead to more unearned runs. Hard hit balls may be more difficult for fielders to handle and could result in errors. It’s just a thought.
Finally, while Brandon Bielak has performed admirably in replacing injured starting pitchers, I think that it’s reasonable to question whether he can maintain that level of run prevention in the future. Bielak has the highest hard hit rate, the second highest barrel rate (behind Ronel Blanco), and the worst Stuff+ ranking among Astros’ pitchers. It’s not unreasonable to expect some regression.