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St. Louis Cardinals: Fatigue Pushing Michael Wacha To Bullpen

Michael Wacha St. Louis Cardinals

On Tuesday, I looked at the offspeed location and movement issues that Michael Wacha faced in 2016. His changeup no longer looked like his best pitch, and his curveball was less effective. The result: batters squared up Wacha at an extremely high rate.

After publishing the article, I thought that, potentially, injury might be causing Michael Wacha trouble. After all, he did hit the DL in August this season and struggled down the stretch in 2015. His injury in 2016 was a recurrence of a shoulder problem that first reared its head in 2014.

This certainly looks like a repeating pattern. Over his first three seasons, as Michael Wacha gets deeper into the year, he has consistently been sideline or become ineffective. Now, I think the cause of his late season slides is not actually injury, but fatigue. The most observable symptoms of fatigue are, of course, injury and ineffectiveness.

If fatigue is the issue, and Michael Wacha is an effective pitcher before he starts showing signs of fatigue, then there is a path to optimizing his value for the St. Louis Cardinals: convert him to a reliever. There are plenty of relievers who succeed with a repertoire similar to Wacha’s fourseamer-changeup-cutter approach. Trevor Rosenthal is the first that comes to mind. If Wacha could establish himself like Rosenthal has, he becomes a valuable bullpen arm and re-gains some trade value.

The first obvious sign that Wacha’s health deteriorates from handling a starter’s workload is simply the amount of time he misses. Over the past three seasons, Michael Wacha averages 1452 pitches from April 1st through June 30th (“first half”). From July 1st through September 30th (“second half”) he averages only 838 pitches. That 614 pitch difference is a 42.2% drop from the first half. Additionally, Wacha has only made it through the second half of the season once, in 2015, and even that was ugly:

Michael Wacha St. Louis Cardinals
Source: FanGraphs

One sign of a fatiguing pitcher is that his location becomes less precise. Additionally, he might start missing higher in the zone. In 2015, Wacha’s only “full, healthy” season, the young pitcher exhibited both signs for three of his four pitches. Interestingly, his changeup is the one pitch that one could argue got better in the second half.

Michael Wacha St. Louis Cardinals
Source: Baseball Savant

I included his cutter heatmaps from first half 2015 (on left) and second half 2015 (on right), where the difference is most pronounced and obvious. In the second half, Wacha developed three cores and, in general, has more red areas all over and around the right half of the zone. Additionally, he missed high more often. Again, while I only included his cutter here, his fourseamer and curveball followed a similar trend.

The first half sample includes 250 cutters, while the second half includes only 137. About half of this difference can be attributed to increased fourseamer usage. Additionally, categorizing pitches into fastballs and offspeed, Wacha maintained approximately a 70-30 ratio in favor of fastballs in the second half, similar to his selection ratio in the first half.

A related sign of pitcher fatigue is the release point. If a pitcher is struggling with arm strength or tiredness, they are more likely to drop their arm slot down, consciously or not. I certainly remember from my playing days (I’m sounding old now, but this was only 4 years ago) that I’d sling it sidearm when my arm was sore. Anyways, here’s Wacha’s horizontal and vertical release points from 2014 and 2016, each season interrupted by a shoulder injury.

Michael Wacha St. Louis Cardinals

While the pattern is most obvious in 2014, in both years Michael Wacha shifted his release point down vertically and wider horizontally (further negative, on the charts) as the season wore on. By the end of each year, he was coming from an entirely different arm than he started the year with. With this new arm slot, the ball is hidden behind Wacha’s body less, giving the hitter more time to pick the ball up.

Furthermore, this affects his pitch movement. He averages slightly less horizontal movement on all four of his pitches in September than he does in April. While there is variance month-to-month, there is a noticeable trend over his nearly eight thousand career pitches tracked.

One last indication of fatigue is apparent in Wacha’s monthly velocities. Below, I’ve charted his career average fastball velocities by month.

Michael Wacha St. Louis Cardinals

At first glance, this appears to counter the point I’m trying to make. Wacha’s average fastball velocity actually trends up as the season gets deeper. Remember, however, that he averages more than 40% less pitches in the second half. So, when he shoulders less of a load and gets additional rest, his velocity kicks back up. If he were in relief, he may be able to keep his velocity all season while managing a smaller amount of innings.

Additionally, Wacha’s lowest velocity month for both his fourseamer and cutter is June. This comes after, on average, throwing 1,042 pitches in April and May. During June of 2014, Wacha was placed on the DL following his 15th start. In 2015, though he pitched the entire season, Wacha was a shell of himself in the second half compared to his first half. In early August of 2016, Wacha hit the DL after his shoulder pain flared up again. This drop in velocity occurring in June might go unnoticed by the naked eye, but appears to signal that Wacha is starting to break down.

I’m no medical expert, but the signs point toward Michael Wacha having consistent trouble managing a starter’s heavy workload. Recently Wacha pointed to a strengthening program and mechanical tweaks which he believes will give him the ability to throw 200 innings. However, this is not a new problem, and this is not a new solution. He said he was at full strength before the 2015 season following an offseason of rehab. Then, he fell apart after June 30th, 2015. Before this past season, the Cardinals expanded their injury prevention effort. Then, Wacha was back on the DL in August.

There is still a positive in this. The fact that Wacha’s velocity ticks up in the second half once he has had time to rest indicates that he could be effective managing a smaller workload. There are plenty of former starters, both from the Minor and Major Leagues, that have transitioned to the bullpen and had success.

By now, both Michael Wacha and the St. Louis Cardinals might have to realize that he is simply not an MLB starting pitcher. That doesn’t mean he can’t still be an effective MLB pitcher, he just needs to come out of the bullpen.


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