Stats All, Folks: What, in the holy name of Batman, is FIP and BABIP? -
Paul Folkemer

Stats All, Folks: What, in the holy name of Batman, is FIP and BABIP?




Either we’ve stumbled into the old Batman TV show, or it’s time for another edition of “Stats All, Folks.”

This is a season-long series that examines the sabermetric side of baseball, giving a primer on advanced statistics and what they mean. I took a look at WAR in the previous installment.

For this second article of the series, I have a two-for-one special: BABIP and FIP, a pair of stats built around a similar premise.

What is BABIP?

BABIP, or Batting Average on Balls in Play, is exactly what it sounds like. It measures how often a batter gets a hit when he puts the ball in the field of play. That means it doesn’t count strikeouts, walks or hit by pitches. It also doesn’t count home runs, since those aren’t technically in the field of play — they’re over the fence.

It’s calculated with this formula: hits minus home runs, divided by at-bats minus strikeouts minus home runs plus sacrifice flies.

A league-average BABIP is around .300. So, on paper, you would expect a batter to get a hit three out of every 10 times he puts the ball in play.

Of course, baseball isn’t that simple. As any baseball player or fan can attest, once you put a ball into play, anything can happen. You could hit a scalding line drive that happens to go directly into a fielder’s glove for a tough out. On the flip side, you could hit a weak, broken-bat infield chopper that nobody can reach for a gift hit.

BABIP aims to shine a light on these disparities. If a player has an abnormally high BABIP during a season — way above his career mark — it’s a strong indication that he’s probably been benefitting from some good luck. The reverse is true, as well; a player with an unusually low BABIP is likely hitting into some tough luck.

That’s not to suggest BABIP is only about luck. It can also reflect a hitter’s skill level. Batters who consistently hit sharp liners will get hits more often than those who tend to hit lazy pop flies. The best hitters can routinely post BABIPs in the .310-.350 range.

Still, teams should be wary of artificially high BABIPs.

To use an Orioles-based example, think back to the club’s July acquisition of outfielder Gerardo Parra in 2015. The Orioles, desperate to find a solid right fielder, seemed to land a great bat in Parra, who was hitting .328 for Milwaukee at the time of the trade.

Parra, though, had a ridiculously high .372 BABIP at that point, a sign he was having freakishly good luck on balls in play. Parra’s career BABIP is .321, which is above average but not near his 2015 mark. That was a warning flag that he was due for some major regression once his BABIP normalized. The Orioles likely knew that, of course, but were hoping Parra’s hot hitting could continue a bit longer.

Unfortunately, the worst-case scenario played out. Parra’s BABIP crashed harder than the club could’ve anticipated, all the way down to .259 as an Oriole. He finished with a meager .237 batting average for the club. Parra wasn’t as bad a hitter as he looked with the Orioles, but also wasn’t as good as he appeared to be with the Brewers.

BABIP applies to pitchers, as well. Pitchers have less control of their BABIP than hitters do, though, because they rely so much on the defense behind them. Sure, some pitchers are skilled at inducing weak contact — witness Zach Britton and his power sinker, which constantly gets batters to hit the ball on the ground. But inducing weak contact is no guarantee of success. If the Orioles’ fielders don’t happen to be positioned in the right place, or they don’t make the plays, some of those potential outs for Britton would turn into base hits and runs instead (through no fault of his own).

When a pitcher has a tough-luck outing in which he’s victimized by bloops, seeing-eye singles and other cheap hits, my wife and I have been known to say, “He’s getting BABIP’d!” (These are the kinds of conversations that occur in the Folkemer household.)

And that brings us to our second stat of the day: FIP.

What is FIP?

FIP is Fielding Independent Pitching. Similar to BABIP, it’s based on the idea that pitchers don’t have a lot of power over what happens once the ball is put into play. So FIP takes those out of the equation entirely. Instead, it focuses solely on the events that don’t involve fielders whatsoever: walks/hit batsmen, strikeouts, and home runs. These plays are entirely under the pitcher’s control.

To calculate FIP, you plug those four stats into a formula — specifically, homers times 13, plus walks/HBPs times three, minus strikeouts times two. That’s all divided by innings pitched. Then you add a “FIP constant” — which varies by season, but is usually somewhere between 3.10 and 3.20 — that puts FIP on the same scale as ERA.

In theory, FIP is like a more accurate version of ERA. It’s meant to show what a pitcher’s true performance level would be if he had a league-average defense and a league-average BABIP. Often a pitcher’s FIP will be similar to his ERA, but not always.

Just as with BABIP, a fluky FIP is something to monitor. A pitcher whose ERA is significantly better than his FIP might be getting helped by good defense and good luck, while a pitcher with a bad ERA but a good FIP might be having an unlucky number of balls fall in or fielders failing to make plays.

A league-average FIP is in the 3.80-4.00 range. The lower the FIP, the better the pitcher.

Again, let’s look at a recent Orioles midseason trade acquisition as an example: Wade Miley. After the Orioles acquired Miley last July, his conventional stats were horrible. He went 2-5 and posted a 6.17 ERA in 11 starts with the club.

A closer look at Miley, though, revealed a 3.79 FIP — more than two full runs better than his ERA. That implies that his overall pitching performance as a 2016 Oriole was much better than the raw stats showed. In fact, Miley’s home run rate, walk rate and, especially, strikeout rate were all reasonably solid for the Orioles. He just gave up lots and lots of hits, which could be partly attributed to bad luck. There were reasons to believe Miley’s 2016 struggles were a fluke and he could redeem himself in 2017.

Sure enough, Miley got off to a strong start in his first four outings with the Orioles this season, allowing just six earned runs and 12 hits in 26 innings. His FIP this season is 3.24. He’s looking more like the solid major league pitcher the Orioles thought he’d be when they acquired him.



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