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June 22, 2008
Ballad of the Fatigued
Controlled Results, Time, and Release Points
The act of pitching is classified as anaerobic exercise due to the short bursts of fairly maximum-effort activity. The more pitches thrown, the more energy is required to complete the activity. Imagine executing a bench press rep at a weight slightly higher than your comfort zone; now, imagine doing that same rep every thirty seconds for a total of forty-five times. It sounds tough, and it would push most humans past their general level of stamina, all the way into fatigue-ville. Keeping that kind of effort in mind, that is essentially the equivalent of throwing 40-plus pitches in a single inning.
Last time out, we explored the effects of these innings with high pitch counts-those in which the pitcher threw 40 or more pitches in the first inning-on their fastballs within the individual inning, and then over the rest of the game, and then we looked at the performance record of the pitchers involved in their subsequent starts. Our results showed that there minimal effects in the actual inning, but as the game went on it became clear that those who threw the hardest suffered the most. They rely on velocity to succeed, and after their long initial inning, they'd lost the zing on their fastballs.
Today the effects of fatigue on release points and how time differential between the first and second inning factors in will be our primary analytical concerns. For starters, though, I spoke to a prominent major league pitching coach regarding the first part of this study, wondering if he looks out for the issues raised. When asked whether or not he has some type of set number at which a red flag is drawn, he said, "We watch to see any change. If it's on the clock, more time between pitches, his body language, I want to see why he's still out there. Twenty-five, twenty-six-unless he had a guy up there ringing him souvenirs [Ed. note: The home plate umpire.] he's not doing so well, and I'm not sure I want him out there."
I also asked if, with a large enough sample size, these results held up would he seriously consider lobbying for the hard-throwers to to be taken out of the game following an early inning with this kind of high pitch count, and he said it would be difficult to justify the decision in the second inning as compared to the fifth inning; ultimately, though, if the results held up and it would be better for both the team and the pitcher's health, he would be in favor.
Controlling the Results
When exploring the results from part one-how fastball velocity and movement changed throughout the course of the game-one major question to ask then is whether or not this is any indication that the 40-plus pitches cause fatigue, or whether what happened subsequently wasn't any different from any other start for these same pitchers. Perhaps they usually take hits in velocity between the first two innings, or perhaps hard-throwers lose velocity this much as the game goes on, regardless of pitch count in the first inning. To get an answer, I found two or three games from each of the thirty pitchers used that saw no more than 24 pitches thrown in any inning, and ones with a very similar time differential between the first two innings as the studied game (this latter element will come into play later).
Here are last week's velocity results, stacked up next to their respective control groups:
Slow Medium Fast IP 40+ Control 40+ Control 40+ Control 1 86.54 86.98 90.35 89.95 92.05 92.12 2 86.27 87.25 88.87 90.14 91.16 92.34 3 86.56 86.77 89.20 89.97 90.81 92.03 4 86.54 87.05 88.80 89.72 90.79 92.27 5 84.99 86.39 89.37 89.97 90.39 92.48 6 84.26 87.32 88.92 89.76 N/A 92.22
This suggests that the velocity discrepancies in the games studied last week are, in fact, different from "normal" games. So what about the vertical movement on these pitcher's pitches?
Slow Medium Fast IP 40+ Control 40+ Control 40+ Control 1 8.55/ 9.06 8.33/9.45 5.58/ 9.13 6.69/8.08 6.81/9.19 6.49/9.09 2 8.24/ 9.21 7.79/8.79 5.91/ 8.49 6.62/7.93 5.80/9.21 6.61/8.99 3 9.30/ 9.13 8.31/9.32 7.03/ 7.91 5.97/8.43 6.50/8.81 6.59/8.94 4 7.91/ 9.89 8.14/8.75 5.51/ 9.57 6.56/8.09 7.88/8.59 6.61/8.96 5 8.72/10.71 8.21/8.84 5.53/ 9.11 6.56/8.86 9.17/7.85 6.59/9.14 6 8.99/ 9.14 8.01/9.14 6.08/10.08 6.29/8.27 N/A 6.66/8.90
There are plenty of numbers in this table but, just like the velocity, these data suggest the games with high pitch counts in the game's initial frame provide atypical results. The hard-throwers lost velocity at an alarming rate as the game progressed, and drastically strayed from their general movement patterns.
While speaking to Dr. Bill Carroll of the University of Mobile, I learned that muscles are dependent on their coordination with nerves-what's known as proprioception. As the muscle tires, proprioception is affected in such a way that it leads to less efficient muscle action, or less efficient coordination amongst the co-contracting muscles during the kinetic chain of the pitching motion. A loss in this coordination can lead to a change in muscle memory, and that in turn produces a flawed delivery for the pitcher.
With that in mind, how were release points affected in these games when compared to the much more normal games? Since release points can be affected by the specific park they were recorded in, I first normalized them to the general cluster of the individual pitcher; this way we run much less of a risk of finding odd discrepancies. Release points are measured in feet as well; a release point of 2.37/6.54 implies 2.37 horizontal feet and 6.54 vertical feet.
Slow Medium Fast IP 40+ Control 40+ Control 40+ Control 1 2.17/6.18 2.61/6.24 2.02/6.12 2.26/6.16 2.37/6.34 2.44/6.33 2 2.16/6.17 2.51/6.28 1.96/6.18 2.24/6.15 2.30/6.27 2.46/6.31 3 2.45/6.22 2.59/6.25 1.98/6.17 2.31/6.17 2.33/6.25 2.60/6.28 4 2.66/6.23 2.55/6.23 2.02/6.11 2.32/6.20 2.31/6.22 2.50/6.34 5 2.48/6.19 2.53/6.27 2.00/6.06 2.33/6.24 2.04/6.12 2.46/6.29 6 2.59/6.26 2.47/6.28 2.19/6.08 2.39/6.21 N/A 2.36/6.28
In the control games, for all three groups the release points are definitely consistent, and not so much in the games with a high first-inning pitch counts. Look at the hard-throwing group on the right (our favorite group to pick on); these pitchers lost significant velocity and vertical movement as the game went on, and their release point steadily dropped as well. That's because both the horizontal and vertical components of the release point decreased as the game went on; this was not the case for the slow or medium groups. The vertical component of the release point tells us at which height the pitch was released; as it decreases, so does the height at which the pitch was released. That in conjunction with a horizontal component that's also shrinking suggests a change in the average arm angle. This was not a case of taller pitchers fizzling out as the game went on, either; the release points dropped for everybody.
Equally interesting is the difference in the release points between the studied and control games, period. They are different, which could potentially be a reason for their struggles in the long-inning game to begin with. Perhaps they struggled in large part due to poor mechanics and a different release point; perhaps they didn't have their stuff to begin with.
Another aspect of fatigue stems from the amount of time off before re-starting the anaerobic activity in question. In the terms of this study, I wanted to look at the effect that the length of time between the last pitch thrown in the first inning and first pitch thrown in the second inning had on these pitchers' velocity and movement. We would have to imagine opposing a notoriously slow worker like Steve Trachsel would be different than, say, getting matched up against a human pitching machine like Mark Buehrle. That is not to say whether the extra time off would be beneficial or not, but it was likely to be different.
As mentioned before, the games I chose as the controls were also in the same vicinity of time-between their part in innings one and two-as the long-inning game. For example, if Derek Lowe's game with a high pitch count in the first inning gave him thirteen minutes between the first and second inning, the one to three control starts had to fall in that general vicinity. The results were not as perfect as they could be in a few years, as vicinity implies a lack of exactitude, but it allows us to gauge the game in discussion against a more standard game from the individual pitchers themselves. The results below are the deltas, or changes, between the first and second innings (so, if someone threw 89.45 mph in the first but 88.32 in the second, their delta would be -1.13 mph). First, here are the velocity results:
Velocity Deltas Time 40+ Control < 8:30 -1.10 1.09 8:30-13:0 -0.62 -1.30 > 13:00 -1.61 0.66
And the movement:
Horizontal Delta Vertical Delta Time 40+ Control 40+ Control < 8:30 0.36 1.27 -0.84 -0.08 8:30-13:0 1.04 -0.39 0.21 -0.38 > 13:00 -0.96 0.17 -0.52 0.03
The pitchers back out there the soonest, those who got back into action less than eight and a half minutes, saw a shift between their control groups and their long-inning games of -2.19 mph, -0.91 horizontal inches, and -0.78 vertical inches. The middle group saw shifts of -1.92 mph, +1.43 horizontal inches, and +0.59 vertical inches. They lost around two miles per hour on their fastball between innings, but gained movement in the long-inning game as compared to the control games. The group that took forever to get back out there saw shifts of -2.28 mph, -1.13 horizontal inches, and -0.55 vertical inches.
As far as conclusions, first, it appears that those who throw hard lose the velocity required to keep their fastballs successful and effective in the games where they had to start off throwing 40 or more pitches in the first inning, which seemingly does not happen as much in their control games.
Second, the release points of all three groups stayed the same in the control games (for all intents and purposes), but fluctuated in the studied games. The slow throwers exhibited no real pattern other than a loss of pattern; the middle group seemed to be the most stable in their fluctuation; and the hard-throwers steadily dropped their arm angle as the game progressed.
Finally, as far as the potential impact of time differential between innings goes, Yerkes, Dodson, and their bell curve of arousal are all likely smiling, because the low- and high-differential groups exhibited entirely negative deltas from the control games to these long-inning games, while the middle group actually showed increases in movement.
Obviously, this is an initial effort, and is therefore far from the final word on this subject. But as far as takeaways, it seems that hard-throwing starters should be treated a bit differently than the rest. If they are going to lose velocity this much as the game progresses, and lose their release point as drastically, it would be of serious benefit to the team to get a fresh arm on the mound.
As the aforementioned pitching coach said, "those with good mechanics will get tired in situations like this, (and) those with poor mechanics will get hurt." Tired or hurt, pitchers falling into either category are not likely to be as effective as those who are fresh and healthy.