There's been some chatter recently in the comments and in the wider Natmosphere about BABIP (batting average on balls in play). This is rough measure of how lucky a batter is: a high BABIP means a lot of batted balls are finding grass instead of gloves, while a low BABIP means that balls are going straight into fielders' gloves instead of finding holes. League-average BABIP is .300, so if a hitter is much above/below that, he's been lucky/unlucky and you should expect his offense to get worse/better as the season goes on.
Here's some of the BABIP conventional wisdom I've been seeing about the Nats lately:
- Danny Espinosa: His .235 BABIP means that his 112 wRC+ is going to take off for the stratosphere.
- Laynce NIx: His 147 wRC+ leads the Nats among regulars, but his .354 BABIP means that his offense will crash hard.
- Michael Morse: His 130 wRC+ is second on the team among regular players, but his .369 BABIP means that he's going to crash even harder than Nix.
These three predictions are wrong. I'll explain why after the jump, and offer a few predictions of my own. Data courtesy fangraphs through June 2nd's game. When I talk about "the team" below, I'm only considering position players with 70 or more plate appearances so far this season.
The problem with BABIP (solution: xBABIP!)
A common objection to BABIP is that it seems unreasonable that every player should have batted balls go for hits about 30% of the time (which is what a .300 BABIP means). What if a hitter is really good at beating out grounders, or hits a lot of fly balls for outs? This is where a stat called xBABIP comes in. Expected BABIP (xBABIP) tries to figure out what each individual player's BABIP should be, based on what kind of hits he gets (line drives are more likely to be hits than grounders, which are more likely to be hits than fly balls, which are more likely to be hits than pop ups) and how fast he is (speedy guys can beat out infield hits and bunts more often). I used this xBABIP calculation. Mind you, this is still a measure that bounces around a lot and takes 500 or more AB to be considered "stable," but it's better than going with the straight league average (it's also a better predictor of BABIP than a player's BABIP from last season).
That's all a long-winded way of saying, "Don't compare BABIP to .300 to determine whether a player is lucky, compare it to his individual xBABIP, instead." Here's a table of Nats showing their BABIPs, xBABIPs, and the difference between the two as a percentage (positive = lucky, negative = unlucky). I also tacked on the rate that they hit line drives (LD%) and get infield hits (IFH%).
Lucky and unlucky
Well, right off it looks like Morse and Nix are the luckiest guys on the team, outperforming their xBABIPs by about 10%! However, they're only 10% lucky, not 20% lucky. Morse and Nix are strong guys who hit a lot of line drives--they're two of the four best line-drive hitters on the Nats. This means you should expect them have BABIPs higher than .300. They will cool off from their current hot streaks, but they won't crash--their BABIPs are only due to drop 30-40 points, not 60-70.
Danny has been unlucky--but only slightly. He's due for about 10 more points of BABIP, not 60. Why? He doesn't hit line drives! Espinosa has the lowest LD% on the team. He also hits the most infield flies, popping up 18.5% of his fly balls (next is Werth at 14.5%, and most of the team is at 10-11%). I think this might be a problem with pitch selection, perhaps chasing too many pitches up for easy pop outs. Until Danny can lay off more of the pitches he can't drive, his BABIP is going to stay low (his xBABIP is lowest on the team), dragging down his BA, in spite of his obvious power.
The real hard-luck BABIP cases are ALR and Pudge. LaRoche's low BABIP is probably explained by his injury--he still hits a ton of line drives, but he's not hitting them very hard, so they're not resulting in hits. Absent the injury, it argues that the Nats should have gotten up to half again more hits out of him for their $8M this year. In spite of his similarly high LD%, Pudge's age may be echoing ALR's injury, perhaps robbing his liners of some of their zing and depressing his BABIP, too. Still, there's a good chance he's having an unlucky run: Pudge's career BABIP is .321, and it was .307 just last season.
The other interesting cases are our CF candidates, Ankiel and Bernadina. The Arm is short about 30 points of BABIP, because he hits the ball hard--granted, he won't be league-average even with that bump. More interesting is the Shark: his .329 BABIP is 50 points too low?! I think we may be hitting a case that challenges the limits of the applicability of the xBABIP formula, compounded by a relatively small amount of PA since his callup. However, he hits the 2nd most line drives on the team, and he is incredibly fast (as measured by his rate of infield hits--which is especially susceptible to SSS at this point). However, if the Shark could eat even half of that extra BABIP margin, he'd be a nearly league-average hitter--that's a valuable bat in CF! This is almost certainly a SSS pipedream, since Bernie's career BABIP is only .295 (although it was .356 at AAA this year...).
Take this xBABIP examination with a grain of salt, as BABIP jumps around a lot and we're still early enough in the season that streaks/slumps dominate the stats. However, it points up some offensive trends based on player's hit types to date:
- Nix and Morse will probably cool off, but stay above league average.
- Espinosa won't get a big injection of offense from turning around his BABIP luck--not unless he cuts down his pop ups and starts hitting more line drives.
- Pudge and LaRoche are the real BABIP losers, and Pudge could probably get his 68 wRC+ up to 80 (still below average, though) if his luck evened out.
- Bernadina will eat up even more hits because SSS doesn't matter to sharks.