Brewers Platoon Splits

Yesterday, Joe Sheehan of Baseball Prospectus wrote his column about the Brewers.  Specifically, he focused on the right-handedness of the team (basically, everybody with power except for Prince) and how that probably isn't a good thing.  Last year, the Crew had an OPS of 859 against lefties and 755 against righties, and that was with Jenkins in the lineup.

So far this year, it's much more dramatic, though some of that is probably due to small sample size.  (We're not going to OPS 966 against lefties for the entire season, unfortunately.  Unless they start cloning Barry Zito, anyway.)

Sheehan notes that the return of Mike Cameron is going to make things worse.  He also suggests that teams with mediocre lefties will consider shifting their rotations to avoid unnecessary lefty vs. Brewers matchups.  Fair enough.

What we're missing here is some context.  Sheehan doesn't come out and say it, but he wouldn't write the article if this were just an interesting factoid: The strong suggestion is that this is a problem.  I don't know that it is or it isn't; a balanced lineup might be ideal, but is this the sort of thing that's going to keep the Brewers from the playoffs?  Should Doug Melvin be calling any and all available lefthanded power hitters?

I would like to do a quick query of all NL teams and find out if any successful teams have had platoon splits of 100 or more points of OPS.  (TheJay, your agent is calling...)  Barring that, let's run some numbers and see what we can turn up.

What's the potential impact?

First, some assumptions.  Last year, the difference was 104 points of OPS; Sheehan gives good reasons why that may increase this year.  Let's say it's 130 points in 2008.  Further, let's say that the Brewers offense is exactly as good it was last year, so figuring roughly three times as many ABs vs. righties, that's an 877 OPS vs. lefties and 747 vs. righties.

If opposing teams make the same decisions (who starts, who relievers) as they did last year, almost exactly 75% of ABs will come against righties.  That's about normal.  If that happens, using the assumptions above and the simple version of Runs Created (OBP*TB), the Brewers are set for about 826 runs.  (Incidentally, the Crew underperformed their simple Runs Created last year; I don't know if there's a good reason for it or if it's just luck.  Also, I'm figuring the OBP/SLG breakdown is the same as it was last year.)

Of course, the more ABs against righties, the worse.  Here are the results, using simple RC over an entire season, for several possibilities:

• 70% vRHP: 840 runs
• 75% vRHP: 826 runs
• 80% vRHP: 812 runs
• 85% vRHP: 797 runs
• 90% vRHP: 783 runs
• 95% vRHP: 769 runs

Comparing 70% to 95%, that's pretty dramatic.  But hold up.  Anything beyond 80% vRHP is probably not going to happen.  75% is normal, and it's not like opposing teams are going to make major roster adjustments just to deal with the lefty-mashingness of the Milwaukee Brewers.

There's only so much they can do

For one thing, bullpens aren't likely to change.  We might see a little less of situational lefties, because there are fewer lefties in the lineup to face, but most teams only have one or two, and they'll be brought in to face Prince just about as often as they were last year.

Further, most starter choices aren't going to change.  The good lefties (Santana, Hamels, Lilly, Hill) aren't going to be bumped from their regular rotation spots, and for much of the season, it would take a roster move to adjust the rotation very much.  If the Pirates want to go with a Triple-A righty or a mop-up guy instead of Paul Maholm, bring it on.  (Not that I think they will.)  Enough rotation shifts like that, and any disadvantage of facing a righty will be outweighed by the advantage of facing somebody who doesn't belong in the rotation in the first place.

Every 5% represents a little less than 300 ABs.  That's a way bigger adjustment than a few rotation juggles are likely to make.  Think of this way.  If the average starter goes 6 innings and gives up about one hit per inning, that's 24 ABs.  So 300 ABs is about 13 starts by righties that would otherwise have been made by lefties, or about one every other week during the regular season.  Not gonna happen, not even close.

I would guess that if teams make adjustments to their rotations, we might see 5 or 6 more righties instead of lefties.  Figure we'll see LOOGYs a bit less, and you've got 150 more ABs against righties than usual, bumping the vRHP up to 77% or 78%.  Total cost to the Brewers: about 7 runs.

If you only read a little bit, read this:

Here's the point.  In a perfect world, we'd have a balanced lineup.  But even if our opponents take advantage of our unbalanced lineup, it'll cost us about one win over the course of the season.  Keep in mind that fixing the problem would never have been free.  If we had tried to get another lefty, we might have gotten a worse defender, or had less money to spend on the bullpen.

Much will be made of the right-handedness of the Brewers lineup, and the platoon splits that will emerge.  There will be days when a righty shuts down the Crew, and this will be the reason given.  Maybe so, but the Brewers are decent offensive team against righthanders, they'll win plenty of games against RH starters, and they'll win a even higher percentage of games against lefties.

The logic of the situation won't convince people not to talk about it, but I hope it will convince you not to take it seriously.