Ryan Romano: What's to blame for Trumbo's strange slump?

As the Orioles go, so goes Mark Trumbo. In the first half of the season, the newest O's slugger put up some of the best offensive numbers in baseball. His .288/.341/.582 triple-slash translated to a 142 wRC+, ranking him 17th among qualified hitters. The club rode that scorching start, and the other hot hitters who backed it up, to a 51-36 first-half record. Since then, their performance has fallen off -- they've gone 16-20 in the second half of the season -- and Trumbo has played a big role in that. From the All-Star Break until now, he's hit a meager .173/.231/.429; his second-half wRC+ of 59 is the 19th-worst in the majors.

This slump is more complex than meets the eye, however. Second-half Trumbo has strikeout and walk rates (26.4 percent and 6.9 percent, respectively) that are virtually identical to those of first-half Trumbo (25.9 percent and 7.0 percent, respectively). And although his ISO has fallen off from .294 to .254, he's still hit for a superb amount of power. BABIP has accounted for most of the difference. In the first half, Trumbo augmented his clout with a sprinkling of singles, as his .327 BABIP indicated. Those hits have vanished in the second half -- his BABIP has cratered to .151, by far the worst mark in baseball.

As you and I know by now, BABIP is a highly volatile metric. When a hitter gets lucky on a few dying quails, he'll see his BABIP rise undeservedly. Likewise, if he smokes line drives directly to opposing defenders, he'll see it plummet without just cause. So has Trumbo just gotten some bad breaks in the second half? His hard-contact rate would suggest that's the case. Pre-ASB, he hit the ball hard 38.3 percent of the time; post-ASB, he's hit it hard 37.5 percent of the time. With only a modest dropoff in quality of contact, maybe he'll see his luck turn around soon.

But simply hitting the ball hard isn't enough: Those balls need to have the right elevation behind them. Grounders won't go for hits as often as liners will, especially for a lumbering player like Trumbo. The spike in his ground ball rate -- from 38.3 percent in the first half to 45.8 percent in the second -- is therefore quite alarming, as is the concurrent dip in line drive rate from 18.5 percent to 9.4 percent. With more worm burners, Trumbo hasn't garnered as many hits; this likely explains the modest decline in power as well.

Looking deeper, though, things don't get much clearer. In the first half, Trumbo feasted on inside pitches. When pitchers tempted him with an offering on the three sections of the plate closest to him, he'd turn on it, rarely putting the ball on the ground and thus notching a high ISO and a higher BABIP. Since then, he's hit far more grounders on those pitches, for no apparent reason. Opposing pitchers have moved away from him, as you'd expect -- in the second half, he's seen 51.8 percent of his pitches on the inner three sections, down from 56.1 percent in the first half. But that's not a massive shift, and he hasn't altered his swing patterns much, either: He's gone from a 57.8 percent swing rate on inner three-fifths pitches to...a 57.0 percent swing rate. Trumbo's approach hasn't evolved, yet the results have changed dramatically.

Pitch type splits offer just as much confusion. Trumbo's first-half success came primarily on fastballs, as he tallied a .412 ISO and .336 BABIP on heaters. That dominance happened because he kept fastballs on the ground 37.7 percent of the time; he's since seen his fastball grounder rate inflate to 45.2 percent, deflating his results in turn (.185 BABIP, .333 ISO). Why hasn't he turned on heaters post-ASB? If we knew the answer to that question, we could likely determine the cause of his slump. That explanation isn't clear, however, if it even exists.

Even with yesterday's victory over the Nationals, the Orioles find themselves two games out of first with a little over a month to play. It's been a dizzying plummet since that electric first half, for both Trumbo and his team. He did knock his 38th long ball of the year last night -- and on an inside fastball -- so maybe he's breaking out of the slump. Or maybe his luck has finally started to turn around. Whatever the cause, we can all agree: A hard-hitting Trumbo is a happy Trumbo.