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Defensive Efficiency 2004
Publication Date: September 28, 2004
How Much Does It Matter?
This is the third of an annual three-part series I do on smarter stats for performance analysis -- the defense. Defense is by far the hardest of the three parts of the game to measure, and as a result the best we can do in the college ranks is a team measure, defensive efficiency.
Perhaps because it's hard to measure, defense tends to be ignored in team construction, but after we look at the results, I'll have some thoughts about how much it matters.
A couple of links:
The top and bottom of the list:
1 0.716 12 0.654 LeMoyne 2 0.715 1 0.672 Texas 3 0.707 3 0.667 Long Beach State 4 0.706 14 0.653 Wichita State 5 0.706 11 0.656 Miami, Florida 6 0.705 5 0.666 Rice 7 0.705 4 0.666 Oral Roberts 8 0.705 18 0.647 Maine 9 0.705 24 0.643 North Carolina 10 0.704 2 0.667 East Carolina 11 0.703 13 0.654 Notre Dame 12 0.702 17 0.648 Tennessee 13 0.702 8 0.662 Cal State Fullerton 14 0.702 20 0.647 Northeastern 15 0.701 6 0.663 North Carolina State 16 0.701 7 0.663 Stanford 17 0.700 15 0.653 George Mason 18 0.699 10 0.656 Lamar 19 0.698 40 0.637 Pace 20 0.696 25 0.643 Baylor 21 0.694 23 0.646 Texas State 22 0.694 56 0.631 St. John's 23 0.693 47 0.634 Central Florida 24 0.693 22 0.647 Alabama 25 0.692 78 0.620 Illinois-Chicago 277 0.620 258 0.564 Tennessee Tech 278 0.619 269 0.557 Centenary 279 0.619 280 0.546 Sacred Heart 280 0.615 282 0.538 Louisiana Tech 281 0.612 272 0.554 Tennessee-Martin 282 0.610 279 0.549 Cal State Northridge 283 0.602 283 0.535 Canisius 284 0.600 285 0.513 Maryland-Eastern Shore 285 0.595 284 0.530 Chicago State 286 0.574 286 0.504 Air Force
Now, really, how much difference does this make? I mean, it's just defense, right? An occasional extra base runner, a little extra hair loss for the coach, but no big deal overall.
Well, let's do a little thought experiment. One nice thing about the no-error-included version of the DE formula (1 - ((H - HR) / (AB - K - HR))) is that it's 1 - the batting average against on balls in play (usually referred to as BABIP), which helps out a bit with some analysis. Since one of the better discoveries of modern analysis is that, to the extent that it's possible to measure it, the only things the pitcher really has any control over are home runs, walks, and strikeouts, we can use this to see how much defense matters, since the rest is a combination of defense and luck.
Now, suppose you have an NCAA Division I average pitching staff at your disposal. In 2004, rounding off a bit but not enough to change things, they would strike out seven, walk three, and give up one home run per game. That means the pitcher gives up four base runners on his own, leaving the defense twenty outs to get. In the list above, we have BABIP ranging from around .285 to .400. To get twenty outs with a .285 BABIP, you're going to give up eight more base runners. To get twenty outs with a .400 BABIP, you're going to give up thirteen, five more a game.
It turns out, though, that the relationship between getting runners on base and scoring is not linear, it's roughly quadratic. Increasing your runners per game from twelve to seventeen, as our bad defense did above, is going to essentially double your runs allowed, all with the exact same average pitching staff. And that's why defense matters quite a bit.
It also turns out that one of the best ways to build a team, and a program, is to find areas that others aren't taking advantage of. Because defense is hard to scout and hard to identify, it tends to get underrepresented in the recruiting process right now, so it might be that trying to build a perfect defense may be a viable strategy for success right now. Certainly paying more attention to while lining up sluggers seems to make sense.
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