It’s the 5th inning, and your starter hasn’t been overly thrifty with his pitches. He has 1 out so far in the inning, and just threw his 88th pitch. What is the fate of this pitcher on this hypothetical day?

If it’s 2010, chances are that a reliever is stirring in the bullpen, and this starter won’t see the 6th inning. Why? Because he will have exceeded his 100 pitch limit by the end of the 5th, or would too greatly surpass it if he went back out the following inning. The 100-pitch barrier proves the undoing of his fun.

Let’s talk about the number 100. It’s big, even, and round. 100 RBI’s in a season is a milestone, as is 100 years spent living on this earth. People celebrate the 100 mph pitch with great excitement, and few have ever been capable of throwing with such speed. 100 wins in a major league season is a fantastic total for a ballclub. And, when a starting pitcher throws 100 pitches, it is time to put in a reliever.

Baseball is too often "all about the Benjamins"

But Why? Why does the number 100 have such power over us? The transition from 99 to 100 is exactly the same as 109 to 110. The three-digitness of 100 just seems to hold some magical power over us, one in which milestones are created and bodies break down.

There is no good reason that we should assume that 100 pitches is the number after which pitchers’ arms will be hurt and effectiveness will be lost. Surely there is some general number for this, but I don’t believe that 100 is it.

Back in the day, pitchers threw 300+ innings a year and finished games without pitch counts. Some got hurt, and some didn’t. Is this the way that starting pitching should be? No, but it represents the other extreme.

Rather, I think the number falls somewhere between 110 and 140. Unfortunately, I don’t really have a good backing for this claim, other than experience and an appeal to the way pitchers pitched in the olden days. Yet, here are a few ways we could find a true pitch count limit…

1. Glycogen testing: Glycogen is the form of carbohydrate that is locally stored in muscle tissue. Glycogen stored in the rotator cuff, for example, is going to be chiefly used up by the rotator cuff muscles. When glycogen gets depleted, muscle performance drops off dramatically, as glycogen is your muscle tissue’s favorite and fastest energy source. If we could find out how many pitches depleted glycogen in the throwing arm and body as a whole to performance-affecting levels, then we would have a good reason to remove a starting pitcher at that point.
2. Velocity readings: Radar guns track every pitch thrown in professional baseball. When a statistically significant drop-off occurs in a game, that would be a sensible place to remove a pitcher. Understand, however, that if a pitcher throws 90 for 100 pitches then sits at 89, that might not be a statistically significant drop – as a loss 1 mph on a 90 mph fastball is only a 1.1% drop. But dropping to 87 from 90 (5%), might represent a more serious drop in performance.
3. Control and game performance: This is the way pitchers were evaluated before pitch counts and radar guns – by visually assessing their effectiveness. If you walk two straight hitters in the 8th, all with high pitches (signs of a dragging arm), maybe your dogs are barking. What’s wrong with this in today’s game? I say nothing, although we do need to make sure a pitcher’s connective tissues can hold up as long as their muscles can…
4. Connective tissue testing: I’ve read studies that claim that ligaments and tendons are more often injured due to highly repetitive stresses rather than one-time acute stresses. This means that you are more likely to injury a ligament or tendon as pitch count rises. Yet, this seems intuitive and obvious. Would you be more likely to tear your quad in the first mile of the Tour de France or the 500th mile? Duh.  But, testing that can tell us how and when connective tissue is becoming stressed to a dangerous level would help us estimate when it’s time to come out of a game.

Maybe all of these tests would tell us that 100 pitches is indeed the generally accepted time to yank the starter…but I would guess that it’s probably not. Differences in genetics, strength, conditioning, body control and experience all play into it, and there is little reason to think that only a handful of pitchers today are capable of throwing somewhat regular complete games. Roy Halladay and Cliff Lee finish about 30% of the games they start; are they superhumans? No. Are they doing something, something secret that the rest of the league doesn’t do, that allows them to go an extra 2-3 good innings? No. Rather, they are just effective pitchers who have established the ability to safely throw 115 pitches every time out, coupled with a coaching staff that understands this. I’m getting my first experience with this as well, as our pitching staff is given a leash of about 120 pitches. If we end an inning at 100, we go back out as long as we are effective. We get to have 15-20% more fun than other starters in our league.

I was discussing this with another pitcher in the bullpen, and he had an interesting point when I posited that there seemed to be a shift in the Majors toward letting starters go longer. He said that because steroids are largely gone, batspeed is down. Because batspeed is down, pitchers are more effective. Because pitchers are more effective, hits and runs are down, and pitchers who give up less hits and runs are less likely to get removed from games. Pretty good logic.

So is the 100 pitch barrier arbitary? I say yes.