The Righty-Lefty Factor in Baseball

11/16/07

It would seem that the single most important function of the manager of a baseball team is to minimize the number of times his right handed batters have to face right handed pitchers, and his left handed batters have to face left handed pitchers. Conversely, he wants to maximize the number of times he can have a right handed pitcher throw to a right handed batter, and vice-versa.

This one factor can take over the course of the latter innings of a game. A manager will frequently take out a right handed batter that has had three hits in the game and replace him with a left handed hitting pinch hitter who is coming in cold off the bench simply because the pitcher for the other team throws right handed. The replaced batter may be the best fielder on his team, and he may have a higher batting average than the pinch hitter, but out he goes.

The opposing manager, though, being of the same school of baseball strategy, will counter by taking out his right handed pitcher, even though he has allowed only one hit over the last six innings, and replace him with a left handed pitcher. Thus, both managers have made major detractions from their teams capability simply in order to comply with the Righty-Lefty conventional strategy.

I wondered how large the advantage is that is gained by getting the upper hand in this Righty-Lefty factor.

I went to http://sports.espn.go.com/mlb/statistics and drilled down to the individual statistics for all major league players, on all teams, in both leagues for the years 2001, 2002, and 2003, combined. This was a total of almost 200,000 at bats. I looked only at batters that were not switch hitters, then recorded their number of at bats and number of hits for appearances against right handed pitchers and against left handed pitchers separately.

I then totaled all of the results for right handed batters against right handed pitchers, right handed batters against left handed pitchers, left handed batters against right handed pitchers, and left handed batters against left handed pitchers, and computed the resulting batting averages.

These are the results:

• Right handed batters against right handed pitchers: 0.264

• Right handed batters against left handed pitchers: 0.276

• Left handed batters against right handed pitchers: 0.279

• Left handed batters against left handed pitchers: 0.256

I also went to http://www,expertcentral.com/search/view-question.cfm?question_id=96667. This link does not seem to be currently operational (this was done on 9/16/2000), but I received the following response from “Cojones”:

View question by Expert cojones Page 1 of 1


09-16-2000] cojones :

I'm happy to report that I did obtain the data you were looking for from one of the contributors to The Big Bad Baseball Annual. This data is for 1980 through
1999, so it covers 20 MLB seasons and thus will smooth out any year-to-year perturbations that might exist:


Matchup, BA, OBP, SLG, OPS

RHB/RHP, .252, .314, .389, .703

RHB/LHP, .266, .333, .410, .743

LHB/LHP, .251, .319, .369, .688

LHB/RHP, .269, .342, .407, .750

http://www.expertcentral.com/search/view-question.cfin?question_id=966679/16/00

Thus, according to my statistical analysis for the years 2001, 2002, and 2003, the difference to a right handed batter in facing a right handed pitcher rather than a left handed pitcher is 0.012, and the difference between a left handed batter facing a left handed pitcher rather than a right handed pitcher is 0.023.

This means that a switch hitter who is hitting .350 when he bats right handed against left handed pitching could reasonably expect to hit .338 if he batted right handed against right handed pitching. In 2007, Raphael Furcal batted as a switch hitter. He hit a hundred points higher when he batted right handed than he did when he batted left handed. Apparently, based on a pretty formidable data base, he would have hit 88 points higher if he had batted right handed against all pitchers.

The disparity for left handed batters is greater, being 0.023. This is easily explained. It is likely that, the more a batter hits against a pitcher throwing from the same side that the batter bats from, the more he will improve his ability to hit that type of pitching. All batters are going to get more at bats against right handed pitching, simply because more human beings are right handed, including pitchers. Therefore, left handed hitters do not get as much practice hitting against left handed pitchers as right handed hitters get hitting against right handed pitchers. Consequently right handed hitters improve more against right handed pitching than left handed hitters improve against left handed pitching.

The data from Cojones (or from Big Bad Baseball Annual), covering the years 1980 through 1999 substantially agrees with the data that I developed. Their disparity for right handed batters is 0.014, and for left handed batters is 0.018.

The fundamental point of this article is that which side of the plate the batter stands on should disappear, as a general rule, from strategy in the game of baseball. If Jim Tracy had not relied on the General Rule in the 2005 season, when he managed the Dodgers, he would have used Alex Cora as a pinch hitter against left handed pitchers instead of against right handed pitchers, even though Cora was a left handed batter. The statistics on Cora were that he hit 60 points higher against left handed pitchers than he did against right handed pitchers. Better yet, he would have never platooned his best infielder at all, but would have played him every inning all year long.

Also would be gone the tragic instances of managers removing starting pitchers who are completely baffling the opposition, and showing no signs of fatigue, simply because the opposing manager puts in a pinch hitter who bats from the other side. The advantage of having a confident pitcher, who is on a roll, will always outweigh the measly 10 or 20 points of batting average that the Lefty-Righty rule brings.