Have The Cubs Forgotten How To Field?

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Of all the elements that allowed the Chicago Cubs to erase 108 years of suffering and finally win the World Series last fall, one of the most important was the team’s stellar defense. Just how efficient were Chicago’s fielders a year ago? Relative to league average, the 2016 Cubs allowed the lowest batting average on balls in play (BABIP) of any team ever.³⁵ As in, since the dawn of big-league ball in 1871, ever. The only team that was even comparable to these Cubs was the 1890 Columbus Solons (a franchise that appears to have folded the next year without explaining its defensive wizardry — or what a “Solon” was).³⁶

Boosted by that historic out-generating vacuum behind them, Cubs pitchers also led the majors in earned run average by the 10th-widest margin³⁷ of any staff since 1901, threatening all sorts of run-prevention records along the way. They allowed 140 fewer runs than the average team, and analytics credit the fielders with something between 50 and 70 percent (depending on the estimate being used) of those saved runs. The Cubs were loaded with stars up and down their lineup, and their pitchers shined brightly when fielders weren’t required, but the importance of Chicago’s glovework was still undeniable.

But the Cubs’ defensive numbers were so off-the-charts last year that they almost seemed unsustainable. And as it turns out, they probably were. This year, the Cubs are right at .500, sitting in fourth place in the NL Central — and their once-dominant defense might be to blame. Instead of allowing the lowest BABIP on the planet, they’re in the middle of the pack defensively; not coincidentally, their staff ERA is unremarkable and they’ve allowed two more runs than an average team. Simply put, Chicago’s secret fielding weapon isn’t working anymore.

This raises a host of questions about the Cubs and about defensive metrics in general. Have the Cubs suddenly, collectively forgotten how to field? Are offseason defections to blame? Or did Chicago just enjoy a historic amount of luck in the field last year — luck for which their fielders received too much credit? And if so, what does that say about our ability to measure defense?

It’s a lot to sort out, so let’s start with the personnel involved. Chicago’s most notable offseason move effectively saw former Padres center fielder Jon Jay slot in for Dexter Fowler, who joined the rival Cardinals. According to Ultimate Zone Rating (UZR), one of the most commonly cited advanced defensive metrics, the Cubs haven’t fared well in the exchange. Although Fowler’s defensive track record hasn’t always been great, he was surprisingly solid a year ago; Jay, meanwhile, is tracking for a very poor defensive season in 2017.

In combination with the retirement of expert defensive catcher and game-caller David Ross, the Jay-for-Fowler tradeoff has helped erode Chicago’s edge in the field. But a far bigger factor is the team’s returning players:

With the exception of new starting catcher Willson Contreras and utilityman extraordinaire Ben Zobrist, every single holdover from the 2016 Cubs has contributed less defensively than he did a season ago. Some have gone from average to bad while others have gone from great to merely good, but there have been big declines across the board.

Such an abrupt and widespread deterioration begs for an explanation, and an obvious one might be that manager Joe Maddon made a tactical change. For example, last season, just as the infield shift hit another all-time high in popularity across MLB, Maddon — famous iconoclast that he is — decided to dial back on using baseball’s favorite new-old tactic. So perhaps Maddon has changed how he’s been deploying his defense so far this year?

Nope! The Cubs are still basically shifting as little as they did a year ago. And the irony is that the BABIP they’ve allowed when shifting is exactly the same as it was last season (.239). The only difference has come on plays when Chicago hasn’t shifted, where opposing hitters’ BABIP has risen from a ridiculously low .258 mark last year to essentially league average this season.

(The biggest difference in pure positioning for the Cubs is that Kris Bryant now plays the shallowest third base in the game. The rest of Chicago’s infield and outfield positions play at roughly the same average depth as they did a year ago, per Statcast data.)

So it’s not the configuration of Chicago’s defense that’s changed. But it wasn’t just Maddon’s contrarian strategy on shifting that was keeping batted-ball averages down last year, it was also his pitchers’ superior ability to mitigate damage on contact. My colleagues Rob Arthur and Ben Lindbergh wrote last season about how the Cubs’ hurlers were inducing particularly easy-to-field balls on contact — which, they postulated, helped Chicago come by that microscopic BABIP honestly (or at least, more honestly than other teams). And certainly the 2016 Cubs allowed some of MLB’s lowest rates of hard contact, according to both exit velocity and other classifications.

But Chicago’s pitchers aren’t doing poorly in that department this season, either, even if they are yielding a few more hard-hit balls this time around.³⁸ If the Cubs’ defensive success was all about inducing soft contact, we’d expect them to be seeing similar defensive results this season, too.

More likely, the Cubs didn’t find a secret BABIP-suppressing hack last year, nor did they forget it this season. Instead, a good amount of Chicago’s defensive brilliance (and subsequent backslide) can probably be explained with the statistician’s most dreaded word: luck. For all the advances we’ve made in understanding and evaluating defense over the past couple decades, and for all the hope that Voros McCracken’s original, earth-shattering finding about pitchers — that they appear to have little control over whether balls in play become hits or outs — was flawed or incomplete, there’s a lot about defense that remains highly unpredictable and beyond the control of fielders, pitchers and managers.

No matter whether we judge a team’s fielding according to a simple metric like BABIP allowed or something more advanced such as UZR or Defensive Runs Saved, defensive performance in one season only explains roughly 10 percent of the variation in the same statistic the following season.³⁹ Although some of that year-to-year noise is due to players switching teams between seasons, it also speaks volumes about the inherent randomness of a baseball coming off a bat. That’s why even a defense as dominant as the 2016 Cubs — or perhaps especially a defense that dominant– will see a big chunk of its advantage melt away in later seasons.

What does that mean for the Cubs? Even granting that last year’s defensive performance was partially the product of good luck, Chicago’s 17-17 record (which the underlying metrics say is about right for how this team has played) is disappointing relative to the amount of talent on its roster. But 34 games is a small sample in a sport where it takes nearly 70 games to reach the same level of certainty in the standings that we get after, say, 11 games in the NFL or 14 in the NBA. So Cubs fans shouldn’t overreact too much: This is still one of the best teams in the majors, and it should eventually put together a record to match. It would be unfair, however, to expect Chicago’s fielding to be as ludicrously efficient as it was a year ago. That historic defense should add to the lore of the Cubs’ curse-breaking World Series win, but that’s all it is now — history.

Happy (belated) birthday, Willie Mays

Instead of pointing out how terrible the San Francisco Giants are these days — they’ve lost 16 of their last 23 ballgames — I’d like to take a second to once again appreciate the excellence of their all-time greatest player, Willie Mays, who turned 86 years old on Saturday.

I’ve written about this before, but Mays was probably the greatest all-around ballplayer in major league history. (The fact that he only won two career MVP awards is one of the underrated travesties of baseball history.) Mays is one of only eight players ever with more than 300 career home runs and 300 steals, and he ranks third all-time in Bill James’ power-speed number.⁴⁰ He also walked more (both in total and on a rate basis) than any member of that 300-300 club except his godson, Barry Bonds. Those two — plus Rickey Henderson, who just missed the 300-homer club by 3 dingers — stand atop the reformulated list if we adjust James’s power-speed stat to also include walks:

And even within that group, what really set Mays apart was his defense. While Henderson was fairly mediocre with the glove, and Bonds’s once-great fielding skills eroded significantly over time, Mays is the third-best defensive outfielder ever, according to Baseball-Reference.com’s defensive WAR. (He was still a Gold Glove centerfielder in 1968, at age 37!) Because of Mays’s unparalleled skills with his bat, feet and glove, he is the only player in baseball history to record at least 120 offensive WAR and 15 defensive WAR.

And he cleared both those benchmarks easily — because of course he did, he’s the greatest all-around player ever. Happy birthday, Willie, and here’s to many more.

Who’s showing the most — and least — plate discipline?

Three years ago, I cooked up a way to see which players were making the best decisions at the plate using FanGraphs’ wonderful “Plate Discipline” stats. Since the site lists the percentage of pitches each player faced that were and were not in the strike zone,⁴¹ along with the share of pitches that were or were not swung at, we can calculate how often a player is correctly identifying a pitch to swing at (because it was over the plate) or lay off (because it definitely was not).

Here are the top and bottom 10 so far this year:

Plate discipline doesn’t automatically equate to successful hitting. Corey Dickerson is swinging at everything that moves — and knocking the cover off the ball. Matt Joyce refuses to offer at a bad pitch, and he can’t buy a hit. But by and large, the hitters at the top of the discipline rankings do tend to be more productive than the ones at the bottom. And they do it mainly by avoiding swinging at junk outside the strike zone.

In terms of predicting hitting effectiveness, a batter’s rate of good decisions on pitches outside the zone is about three times as important as his rate of good decisions on pitches inside the zone. In other words, it’s not the end of the world if you let a strike go by without swinging — who knows, maybe you’re waiting for your pitch. But few batters can get away with flailing at bad pitches for long. For every Dickerson or Vlad Guerrero, there’s an undisciplined hacker who let the pitcher trick him into getting himself out.