Reality Check: Defensive Shifts

Tom Verducci writes about baseball for Sports Illustrated and talks about on the MLB Network. He's a smart guy and a great writer. He's passionate about the game as well, writing on occasion about ways it could be better. He did so last week, proposing that baseball do something to limit defensive shifts: moving fielders to one side or the other of second base in order to take advantage of hitters' tendencies to hit the ball there. You know, like this:

Verducci cites the situation pictured above in particular, when the player at the plate is lefthanded, he tends to hit balls to the right side of the infield, and, in addition, he's slow. (I can't speak to the speed of the guy at the plate in this picture; I can't make him out.) He cites slow left-handed batters who pull having down years: Chris Davis, Ryan Howard, Jay Bruce, Adam Dunn, Brian McCann, Shin-Soo Choo, David Ortiz, and Adrian Gonzalez, among others. He has a pretty convincing table: batting average on balls in play (i.e., excluding at bats that result in strikeouts or home runs) for left-handed hitters when they hit the ball to the right side of the infield:
   2005   .379
   2006   .386
   2007   .353
   2008   .358
   2009   .350
   2010   .351
   2011   .332
   2012   .313
   2013   .323
   2014   .301

Verducci:

In 2010, Howard, McCann, Ortiz, Bruce, Dunn, Choo, Curtis Granderson and Adam LaRoche all were among the best lefthanded hitters in the game. None of them were All-Stars this year. Fewer hits to the pull field – into the shift – is one reason. Throw in former All-Stars Mark Teixeira and Carlos Beltran, two more slow-footed sluggers (and using only their numbers batting lefthanded), and you can see how the shift is harming lefthanders...

Ignore that some of those guys haven't been good for years. His point, that the shift's affected lefties since the Tampa Bay Rays started becoming shift-happy in 2008, seems to be borne out by the numbers above. His solution: That baseball should look into establishing an "illegal defense rule" that'd limit the number of infielders on either side of second base to two. 

Verducci's proposal met with a fair amount of criticism on the Internet, partly because he's proposing a pretty significant change to the rules of the game. I don't really buy that. The rules of baseball aren't inviolable; we added replay and removed home plate collisions this year. If there's a problem in the game, let's address it.

The problem I have is that I'm not sure the response Verducci's proposing--limiting defensive shifts--will address the problem of a decline in offense, simply because there's not a lot of evidence I can see that shifts are the culprit. I'm going to show you a somewhat busy table, so let me explain the columns. The first one, Year, is self-explanatory. BABIP is the batting average on balls in play--that is, the batting average when the batter puts the ball in play (doesn't strike out, walk, get hit by the pitch, etc.) and doesn't hit a home run. Ground is the batting average on ground balls. L vs. L is the batting average for left-handed hitters--the focus of Verducci's research--against left-handed pitchers. L vs. R is the batting average for left-handed hitters against right-handed pitchers. If defensive shifts are hurting offenses, particularly with lefties at the plate, we should see all of these batting averages decline with time, as shifted fielders turn what used to be hits into outs. Here's the table:
   Year    BABIP  Ground  L vs. L  L vs. R
   2005    .295    .233    .295     .299
   2006    .301    .236    .294     .302
   2007    .303    .239    .301     .312
   2008    .300    .237    .298     .302
   2009    .299    .232    .286     .299
   2010    .297    .234    .299     .298
   2011    .295    .231    .291     .301
   2012    .297    .234    .287     .299
   2013    .297    .232    .293     .300
   2014    .299    .237    .297     .307

Do you see any evidence from those number that defensive shifts--which have grown in popularity especially in the last couple years--have hampered offense? I can't. As of today, the batting average on balls in play at its highest level since 2009. The batting average on grounders is the highest it's been since 2008. Left-handed hitters are hitting better against lefties than any year since 2010 and against righties since 2007. Offense is surely down, but it's not because defensive shifts are resulting in plummeting batting averages. So I don't see a need to legislate against shifts.

As to why offense if down: batters are striking out in 20.3% of plate appearances, the most in history--the rate's risen for nine straight years--the walk rate's declined for five straight years and is now at its lowest level since 1968, batters are hitting balls on the ground,  which produce a lower OPS than balls hit in the air, at the highest rate since stats became available in 2002, and the percentage of fly balls leaving the park has declined for two years, to the lowest level since 2011. That's why. Sounds like a problem of good pitching rather than innovative defense.