bronson arroyo is a badass too

I expect the real reason baseball will eventually return to the four-man rotation will be the simplest of all: it helps win games. The five-man rotation is not on that evolutionary path; it is a digression, a dead-end alley.

- Craig Wright, The Diamond Appraised, 1989

Today Bronson Arroyo is starting on three days rest instead of the usual four. Why? Because he marched into manager Jerry Narron’s office demanded to start a day sooner.

Bronson was anxious to end his personal four-game losing streak, and also wanted to set up the rotation so he could face the division rival St. Louis Cardinals twice before the end of the season instead of just once.  You gotta love a guy who wants the ball in the biggest situation, and is willing to - nay, demands to - pitch on short rest to get those chances, so naturally, Narron and pitching coach Tom Hume were not about to stand in his way, especially since Arroyo has been the ace of the staff for the Reds this year.

But Bronson also had another reason for wanting to pitch on short rest: he felt he would actually pitch better.  Bronson has noticed over the years that the more days off he has between starts, the less sharp his command is, and he is convinced that three days of rest is the most optimal.

“It just seems like we’re sitting around so much waiting to start with so many off-days all the time,” Arroyo said. “I’ve been wanting to go to a four-man rotation all year.”

A four-man rotation in this day and age? Is Bronson Arroyo crazy?

Actually, probably not. As starting pitchers are increasingly held to 100 pitches or less, they are finding that they recover much more quickly from starts and are anxious to get back out there.  For example, both Brad Penny and Aaron Sele of the Dodgers this year have volunteered for bullpen duty in between starts when an off day would force them to pitch on five days rest.

Moreover, evidence is mounting that a four-man rotation is not as detrimental to pitchers arms as managers have assumed for the last 20 years or so.  This past off-season, Baseball Prospectus’s Keith Woolner did a study which found that even in the days before the 100-pitch limit, pitchers who pitched on three days rest statistically did no better or worse than pitchers pitching on four days rest, and that whereas pitching over 100 pitches in starts correlated strongly to arm injury, pitching on three days rest correlated little or not at all.  Furthermore, evidence seemed to indicate that pitchers who pitched on three days rest but were held to a reasonable pitch count actually pitched better than pitchers pitching on four days rest.

Which is all to say that Bronson Arroyo, in addition to being a badass, may actually know what he is talking about. It seems reasonable to assume that with pitchers throwing far fewer pitches per start than ever before, they should be able to start a little more often.  After all, going from a five-man rotation to a four-man rotation only adds about 5 or 6 more starts per starter over the whole season.

If teams returned to the four-man rotation with today’s 100-pitch count limit, we could easily see a return of the 40-start, 275 IP, 25-win season, without a significant increase in the risk of injury. Moreover, teams with the daring to implement the four-man rotation would gain significant advantages over their opponents, allowing many more of their innings to be pitched by their best pitchers (20-30 less starts by a fifth-starter type), and clearing a roster spot for an extra reliever or bench player.