Game Theory

Batting Average Assumptions For 2010

When it comes to hitters, the only standard rate-statistic is batting average. Pitchers, well, they get their ERA and WHIP, so I’ll deal with those in an upcoming article. Today, I’ll try to primarily focus on quite possibly the most difficult to quantify of all the statistics in your standard roto-league.

First, we’ll have to suspend disbelief, unless you’re a Twins fan, I suppose. Joe Mauer probably isn’t going to duplicate his .365 Batting Average in 2010, but for the purpose of this example; We’ll just assume he does.

So Let’s take these Five BA Leaders and take a deeper look inside their numbers:

Name	AB	H	AVG
Joe Mauer	523	191	0.365
Ichiro Suzuki	639	225	0.352
Hanley Ramirez	576	197	0.342
Derek Jeter	634	212	0.334
Pablo Sandoval	572	189	0.330
Albert Pujols	568	186	0.327
Todd Helton	544	177	0.325
Miguel Cabrera	611	198	0.324

All great hitters and if you’re drafting any of ‘em, you’re going to get a nice little bump in the Batting Average category.  However, just how valuable is Joe Mauer’s .365 compared to Ichiro’s .352 or Jeter’s .344?

Well, the easiest way for me to quantify their value is to just add ‘em to everyone’s favourite three-outcome player: Adam Dunn.  In 2009, Dunn had 146 Hits in 546 AB — good for a .267 Batting Average.  Ideally, we’d compare them to the replacement level BA player on your roster, but using Dunn provides a tangible example.

Name	AB	H	AVG	+DUNN’s AB	+DUNN’s H	Total BA
Joe Mauer	523	191	0.365	1069	337	0.315
Ichiro Suzuki	639	225	0.352	1185	371	0.313
Hanley Ramirez	576	197	0.342	1122	343	0.306
Derek Jeter	634	212	0.334	1180	358	0.303
Pablo Sandoval	572	189	0.330	1118	335	0.300
Albert Pujols	568	186	0.327	1114	332	0.298
Todd Helton	544	177	0.325	1090	323	0.296
Miguel Cabrera	611	198	0.324	1157	344	0.297

You’ll notice the batting average decrease is disproportional, as expected.   Suffices to say, hitting .365 over 523 ABs is an astounding achievement but it looks a lot better than it actually contributes to the BA category. Ichiro’s extra 100 at-bats almost completely negates Joe Mauer’s original 13pt advantage.

The easiest way to view batting average without putting too much thought into it is to subtract a single point for every 25 (or so) ABs below 600 and to add a point for every 25 or so above that number.  This is just a rough work-around and the effect will decrease as you get closer to your team’s average BA.

Here are some of the players that are overvalued based on limited ABs:

1. Chris Coghlan, .321 AVG  — 504 ABs
2. Jason Bartlett, .320 AVG — 500 AB
3. Erick Aybar, .312 AVG — 504 AB
4. Magglio Ordonez, .310 AVG — 465 AB

…and the undervalued players:

1. Ichiro Suzuki, .352 — 649 AB
2. Robbie Cano, .320 — 637 AB
3. Braun, Jeter, and Miguel Cabrera as well.

Obviously, this doesn’t take into account WHY a player missed his AB, just that he missed them.  In some cases, players miss AB due to their position in the line-up or even the line-up itself.  A catcher will generally take more off-days than a fielder and a lead-off hitter will get more ABs than someone in the 9-hole.  In other cases, players just refuse to take a walk.  These variables stay pretty constant from year to year, though.  Ichiro’s Batting Average is consistently over a larger number of ABs because of the previous reasons.  If a player posted a solid batting average in 2009, but missed the 600 AB mark due to injury; it’s best to just look at his historical ABs, assuming that he hasn’t changed teams.

Your best bet is to focus on good hitters that bat in the top-3 of a good offensive line-up while converting his plate appearances into hits rather than walks.

Also keep in mind that the reverse is true:  Jimmy Rollins’ .250 Batting Average over 672 at-bats hurts a lot more than Russell Martin’s .250 Batting Average over 505 at-bats.

The worst case scenario is to both overvalue Joe Mauer’s .365 batting average while undervaluing the impact of Jimmy Rollins’ .250 Batting Average.

Say you drafted Joe Mauer’s .365 BA and Jimmy Rollins’ .250 Batting Average.  At first glance (a straight average) would give you a .308 Batting Average which makes for a solid draft-strategy.  However, if you factor in the number ABs the averages were achieved over, you’ll end up with a .300 BA — Not nearly as impressive.

A Caveat:

It’s almost impossible to predict a players Batting Average within 10 points, so if you’re feeling a certain player for a break-out year — Go ahead and take ‘em.

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