Tuesday, May 15, 2007

Pitching and Defense

Obviously Boston improved their pitching staff with the addition of Matsuzaka but almost a quarter of the way through the season the most noticeable improvement in the team has been their defense. Many argue that Boston was a great defensive team last year and point to their low error total and high fielding percentage. But fielding percentage is a very deceptive stat and can lead someone to think that a poor defense is good and vice versa. The problem with fielding percentage is that it only takes into account errors committed and does nothing to rate the speed of a defense. Putting yourself in a position to make a play is just as important, if not more important than making the play. Take a hypothetical 10 ground balls hit to two different shortstops. Shortstop A (Derek Jeter) is has a great glove and accurate arm but is very slow and has poor reaction time. Shortstop B (Miguel Tejada) is very fast and has great reaction time but occasionally misplays a ball with his glove or makes an errant throw every once in a while. In the 10 balls hit to Shortstop A (Derek Jeter) he fields 6 of them cleanly and throw the runner out at first, pumping his fist after each out. But 4 of the balls hit in his area go for hits. Shortstop B (Miguel Tejada) has 10 balls hit in his area, 8 of which he gets to because of his superior range but one goes for a hit and one he commits an error throwing to first base because he was off balance because he had to run 20 feet to reach a ball that Shortstop A would never have come close to. Now if you only use fielding percentage as a measure of defensive ability you would say that Shortstop A (Derek Jeter) is better than Shortstop B (Miguel Tejada) because his field percentage is 1.000% and Tejada’s is .888%. But you would be ignoring that of the 10 balls hit in his area Tejada turned 8 of them into outs and Jeter only turned 6 into outs. If you only consider the results an error is the equal to a play not made. This can be applied to team defense as well. If you only look at fielding percentage you are missing the more important stat which is the rate in which balls put into play are turned into outs or Defensive Efficiency. This brings me to the Red Sox this season. Last year many said that the Red Sox were a great defensive team due to their fielding percentage being the best in the American League when in fact their defensive efficiency was 12th out of 14 teams. Alex Gonzalez and Mark Loretta had undeserved reputations as great players at their respective positions. To be fair like Jeter both were very sure handed and had accurate arms but were very limited in their range and didn’t get to many balls hit in their area. In effect they were more Jeters than Tejadas. This season we have the much speedier Julio Lugo at short and Dustin Pedroia at second as well as a healthy Coco in center. This has lead to the Sox currently being 2nd in the league in defensive efficiency. At the same time their fielding percentage has dropped to 12th in the American League which makes some say that the loss of Gonzalez and Loretta has hurt their team defense. But the exact opposite is true. So with a great number of balls hit into play being turned into outs the pitching staff’s ERA has been lowered as well. When you look at a pitcher’s stats the ones most often used to judge their abilities are the stats that are the most dependant on the quality of the defense behind them (Wins/Losses/ERA). Taking Josh Beckett as an example I think his 7-0 start can be attributed to 3 things; fewer walks, giving up fewer homeruns, and most importantly a vastly improved defense behind him.

4 comments:

Anonymous said...

well done young man - and only one paragraph!

-- John

akboognish said...

So Bill James has to know this stat, right? You think they were going after better defensive efficiency or just got lucky?

Dewy24 said...

definitely. i think it was a very conscious decision by theo to improve the defense up the middle. lugo is just better defensively and offensively than alex gonzalez. and pedroia projects to be a similar hitter to loretta based on his performance in every level of the minor leagues. plus he was 4 million dollars cheaper and has a better glove with more range.

Dan said...

You forgot to factor in the plays in which Shortstop A bashes and bloodies his face diving into the stands for pop flies against Division Rival A (the Red Sox) - most commonly known as Gamer Efficiency.