Chicago Cubs: Pitching BABIP, defense, luck and how it all ties together

The Chicago Cubs’ pitching staff hasn’t been nearly as good as last year’s, especially in BABIP. We look into what could be the cause and how it’s affected the team’s slow start.

Out of all the sabermetric stats that exist out there, BABIP is one of the most useful. Standing for ‘batting average on balls in play,’ it’s used to determine how often non-home run batted balls drop in for hits.

Over at Fangraphs, they’ve deduced that BABIP is influenced by three factors: defense, luck and talent level. For example, a hard hit line drive may be caught by an elite second baseman, but go for a double when hit to a platoon player.

BABIP is not only useful for evaluating hitters but pitchers as well. Once the ball leaves the pitcher’s hand he no longer has control of what happens, therefore pitcher’s BABIP is more influenced by luck and defense than talent level.

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Last season the Cubs had a whole lot of luck and defense. They ranked first in pitcher’s BABIP with a .255 mark, 27 less than the next team. They ranked first in pretty much every defensive stat that matters, and some people have heralded them as the best defensive team of all time.

Was it just luck?

But hold the phone. The Cubs last year were only 21st in fielding percentage and had the 8th most errors. What this tells us is that their low BABIP was likely more based on luck than defense, and so far this season that luck has run out.

The Cubs are currently 11th in pitcher’s BABIP with a .297 mark, with their starters having a whopping .317 number, 3rd most in baseball. While the defense certainly hasn’t been like last year’s, such a stark difference is very intriguing.

By looking at the difference in BABIP as well as the team’s pitching performance some questions arise. First, are hitters simply hitting the ball better? By using Fangraph’s nifty batted ball tab we can see just how hard (or soft) the balls from Cubs’ pitchers are being hit:

As you can see, this year the Cubs so far are giving up a little bit more hard contact than last year. By the same token, they’re also allowing more soft contact. All in all, there isn’t enough variation to say with confidence that opposing hitters are squaring up the ball more.

So if it isn’t opposing hitters (aka the talent level) then it’s mostly some combination of the other two factors that is affecting BABIP and overall pitching performance. Let’s start with defense.

So far the Cubs are 3rd in the league in errors with 33. That puts them on pace for about 134, which would be 33 more than what they had last year. Currently, the Cubs have 25 more total runs allowed than earned runs, which means 25 runs extra runs have been scored due to errors and wild pitches. That number last year after 40 games? Nine.

So it appears that a drop off in defense has played a big part in the team’s lackluster start. But since errors don’t count towards BABIP, how do they affect the stat?

Well, it doesn’t really. However, it can help explain how the Cubs have given up more runs than they did last year. Here’s the change in run totals from this point of the season last year to this year:

Of course, more errors aren’t the only reason for the increase in runs. However it certainly hasn’t helped, and more errors mean more runners on base, which ultimately brings us to the third factor: luck.

It’s common sense that the more runners you put on base the more runs the other team is likely to score. And being that the Cubs’ BABIP last year was unsustainable it makes even more sense that more runs have been given up.

The combination of more runners on base via errors coupled with the inevitable uptick of BABIP means that opponents are more likely going to get hits with runners on base, which naturally leads to more runs.

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The pitchers’ high marks in BABIP, particularly the starters, have been pretty unlucky. However, history tells us that the number will probably trend back down to the mean as the season progresses.

The baseball gods can be cruel sometimes, and they’ve definitely been so to the Cubs. Nonetheless, as unlucky as the Cubs have been, it’ll eventually start to fade. If the numbers are still this way two months from now then it’s a different story, but for now, it’s just a trend that hopefully won’t continue much longer.

*Stats accurate as May 18