Looking Into Workload For Hitters
Pitchers are continuously being monitored. From the amount of throws that they make in a given start, to how many throws they make in a bullpen. There are even instances where pitches are limited with how much they can throw on the side. The general idea of pitchers is that there are only so many throws that they can make at their top quality. The main goal being that pitchers are most fresh when it matters most. How often do we flip this around to focus on the offense side of the ball. How often do we consider a hitters workload for a given day? Its an area that I think deserves more attention.
The Cape Cod League has a partnership with Blast which has been a big value add for us as a staff in Wareham. Blast supplies us with a sensor for each player. Each day for on field batting practice we ask players to wear them for both cage work, and on field BP prior to the game. The goal for this write up is to look at players swings and kind of estimate at what swing number do players performances start to dip and potential bad habits set in. How often are we asking our hitters (to make an analogy) to throw 50–60 pitches in the bullpen before the game begins?
As you can see from this plot the more swings that a player takes the effects of fatigue start to set in. Sound obvious I know. Players start to see declines in Bat Speed roughly after the 25th swing during practice. If we dig deeper we can see that by their 40th swing in Batting Practice we see significant declines. But it isn’t just bat speed that suffers as players take more swings. We see similar effects when it comes to Blasts Power Metric, Rotational Acceleration, Peak Hand Speed, and longer time to contact. As players get tired their swings start to break down a little bit.
The biggest take away should be that once hitters reach 25 swing during batting practice we should be careful with any workload that we add from that point forward. We should make the assumption that hitters only have 15–25 of their highest quality swings in them. (Obviously this differs slightly for each hitter)
The effects of fatigue on a players ability to move the bat quickly and effectively during practice seem to be pretty obvious. Anyone who is reading this would argue that a players 40th swing would be just as high quality as their 10th.
The deeper issue that we need to look at is how a players bat path potentially changes due to Workload. At what point do we start to see the impact of fatigue make unwanted mechanical changes in players. Players Attack Angle changes pretty significantly over the course of 40 swings. Along with a sporadic changes in Vertical Bat Angle.
Similar to the metrics we examined above we start to see changes in players swing occur around the 25th swing in Batting Practice, along with more pronounced changes around swing 40 .
The takeaway here should be that we have a small window for players to take their most effective swings during practice. Coaches should be cognizant of this when designing practice. This is a balancing act though. Of cause there are situations where players can probably take on more of a workload. Similar to the gym there are going to be days where you increase the work load, and there are days that you are going to have to scale down the workload. The goal should be to balance the amount of swings that a player takes.
But in terms of keeping players fresh on a daily basis the number would seem to be around 40ish swings. To me making sure that players are challenged in those first 25–30 swings should be the goal. Those are the swings that are clearly the most high quality.
Hitters are notorious for taking a lot of swings. They show up early, work long days, swing a lot. The consideration to put Hitters on a “Swing Count” shouldn’t be dismissed out of hand. Hitters get tired, and over the course of a season it is more difficult to manage the balance between development (more swings), and being game ready (being fresher). I don’t think we have a clear picture of what is perfect, but I think that this is a start.
Thanks to our lead hitting analyst Jack Byrne for digging into this idea.
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