Have Bat, Will Strike Out or Homer

Baseball has always been a numbers game, but players and teams are getting smarter than ever — and fans are, too. Throughout The Ringer’s 2017 MLB preview, in a series we’re calling "How to Baseball," our experts will explore the developments that stand to change the way the game is played and consumed. We’ve never known more, and while knowledge is power, it’s also a wellspring of questions. We hope to answer some of them — and to remind you all to bunt wisely.

The list of 2017 home run leaders starts with two names whose high placement seems significant. Bryce Harper leads the world with eight dingers, while Yankees youngster Greg Bird is next with seven. Both players suffered confirmed or suspected right shoulder problems last season and failed to build on their 2015 breakouts: Harper declined by six WAR amid multiple injury reports that the Nationals denied and Harper didn’t address, while Bird had season-ending surgery last February to repair a torn labrum. Their numbers now seem to suggest that they’re back to full strength and bound for big years.

Until, that is, you look a little lower on the list. Three other hitters have hit seven bombs: Jabari Blash, Chris Marrero, and Pete O’Brien. (I’ll wait while you Google.) Riiight, that’s the reminder we needed. This is still spring training.

As we’ve learned from many a March mirage, individual players’ spring training stats aren’t especially predictive of regular-season performance. Sometimes the outliers are telling — research has shown that extreme performances in sensitive statistical categories do improve a player’s outlook for the upcoming year — but between the small samples, the weak competition, the sporadic starts, and the incentive to save one’s strength for games that matter more, the noise swamps the signal.

On a macro level, though, it’s worth paying close attention to spring training. Grapefruit and Cactus League hitters have already combined to make more than 36,000 plate appearances, with a few more days to go. That’s enough to tip us off to changes that could be coming in the regular season, despite the spring’s different conditions.

In recent years, much of the discussion about baseball’s on-field future has revolved around the league’s strikeout rate and home run rate. The former is on an inexorable incline that’s threatening to send singles to the endangered list. The latter sustained a sudden, mysterious leap at the 2015 All-Star break that held up through last season, producing the highest home-runs-on-contact rate (HR/(AB-K)) of all time. After a winter-long wait for fresh data, this spring could be the bellwether that tells us where strikeouts and homers are headed next.

Spring strikeout percentage has an extremely strong relationship with regular-season strikeout percentage, boasting a .98 correlation from 2006–16, the years for which spring stats are available via MLB.com. (A correlation of 1 would indicate a perfect positive relationship in which the two stats move in tandem.) And despite some tenuous signs that the called strike zone’s dimensions could be contracting this spring after its years-long expansion stalled last season, the strikeout rate still seems to be rising. This year’s 20.2 percent — an increase of 0.8 percentage points relative to last March — is the highest spring mark in our 12-season sample. Baseball’s lack of contact is, unsurprisingly, still growing more acute.

Over the last 11 campaigns, the regular-season strikeout rate has been 1.4 percentage points higher than the spring rate on average, maybe because the pitchers catch up to the hitters as the season wears on. If we add that typical margin to this spring’s rate, we get an expected regular-season figure of 21.7 percent, which would yield about 1,000 more strikeouts than we saw last season. That result could only strengthen commissioner Rob Manfred’s desire to formally raise the strike zone’s lower bound from beneath the kneecap to the top of the kneecap in 2018. (As that use of anatomy indicates, the strike zone is super precise.)

With fewer balls put in play every season, the record home run rate is the only thing keeping offense afloat. Although those extra home runs could have come from a combination of factors, the research Rob Arthur and I conducted last year led us to believe that a change in the ball was the likeliest culprit. In our estimation, none of the other explanations proposed — PEDs, swing changes, an influx of young power hitters, and many more — seemed sufficient to produce such a dramatic effect in a way that was consistent with the timeline, which involved an almost instantaneous mid-season change. And if the home run rate can skyrocket without warning, then in theory it could crater, too. (Remember the rabbit ball?)

Over the last decade, the relationship between spring and regular-season home run rate on contact has been weaker than that of spring and regular-season strikeout rate, but still strong overall (.73 correlation). Last spring’s rate was the highest on record, and sure enough, it augured a record-setting regular season. As Opening Day approaches, this spring’s rate has reached another new high, which suggests that whatever’s happened with homers since the second half of 2015 hasn’t run its course yet.

Here we have a caveat to include: This was a World Baseball Championship year. And while previous WBC years don’t seem to have skewed spring strikeout rates, there’s some evidence that they have had a home run effect. Prior to last spring, the three highest HR/contact rates in the spring sample came during WBC years: 2006, 2009, and 2013. That might mean that this spring’s higher-than-ever HR/contact rate is artificially inflated, but with only three earlier WBC data points to draw on, it’s tough to say for sure. Given all of the chatter about batters employing uppercuts and aiming for flies this year, it might be worth noting that the ratio of ground outs to air outs is down only infinitesimally from 1.27 last March to 1.25 now, which isn’t low compared with some previous springs.

We’re inching ever closer to a point where the "Three True Outcomes" crowd out contact to an uncomfortable degree. Baseball has never been blessed with so many charismatic and preternaturally talented young hitters, or so few chances for them to make plays in the field and fly around the bases. Thus far this spring, the rise in strikeouts seems to be outweighing the rise in home runs: Compared with last year at this time, OPS is down 13 points, and scoring — which has also tended to move in the same direction as the regular-season rate (correlation of .66) — is down .09 runs per game. If this spring is a preview of the rest of 2017, expect recent trends to continue: Whiffs will become increasingly common, balls in play will become increasingly scarce, and a sky-high home run rate will prop up run totals enough to prevent any panic. Just don’t expect Manfred to sit quietly while the water starts to boil.