No, you do not need to get him some work

We’ve all heard managers say it before. When a good relief pitcher is brought into a blowout game, whether his team is winning or losing, it’s almost inevitable that the team’s manager will explain that the reason this good pitcher appeared was so that he could “get some work,” and the general feeling is that it is to keep the pitcher from getting rusty. Take Friday’s 11-3 win over the Detroit Tigers, where Mark Lowe threw one inning, allowing 2 hits and 1 run while recording a strikeout. He threw 18 pitches. Kirby Arnold of the Everett Herald noted on his blog that “getting some work” was Wakamatsu’s motivation for putting Lowe in the game.

"Wakamatsu said Lowe is fine physically, noting that his fastball reached 97 mph tonight, but that he was rusty after having not pitched since April 10."

Well, honestly, I think that’s a load of crap, and I set out to prove it.

Generally speaking, managers will only use this excuse with good pitchers. No manager puts, say, Sean White in the game to get him some work. When a manager uses this excuse it’s generally for setup men and closers who haven’t pitched in awhile. The managers must believe, then, that a relief pitcher’s performance will suffer if he does not pitch regularly. Perhaps managers believe the layoff may make them lose the strike zone, or become more hittable. Is this true? Or are managers simply wasting an appearance from one of their better relievers in a game that doesn’t matter?

I looked at Mark Lowe and five closers’ 2009 appearances after which they hadn’t appeared in a game for at least three days. What I found was unsurprising. Though small sample size applies, these six pitchers generally performed better on longer rest than their overall season line. So it would appear that having extra days between appearances improves pitcher performance instead of diminishing it. Seems logical enough to me. Anyway, enough words, it’s time for numbers!! Hooray!

The first set of numbers: Stats accumulated when pitching on 3+ days of rest.
Numbers in parenthesis: Overall 2009 stats.
P/IP=Pitches per inning.

Too see all of figure 1 just click on it. Our blog is too narrow to see the whole thing.

As you can see from the tables above, it would appear that when pitchers are more rested, their stuff becomes harder to hit, but also slightly more difficult to control. However, their walk rate goes up less than one walk per nine, while their strikeout rate goes up by more than 2. Obviously, 90 innings is an extremely small sample size, but being that each reliever’s performance changes similarly, I’m willing to say that this is probably significant.

So, next time your manager says “he just needed to get some work in” facepalm away, because your manager is wasting one of your better pitchers’ appearances in a meaningless game. If the M’s need Mark Lowe this afternoon and can’t use him since he pitched on Friday, manager Don Wakamatsu will have essentially removed one of his best late inning weapons for a game for no reason. Take note, MLB managers. You don’t need to get your pitchers extra work to keep them from getting rusty, because they don’t get rusty. They get better.