This past winter, the Padres inked veteran first baseman Eric Hosmer to an eight-year, $144 million contract that included an opt-out after the 2022 season. Hosmer was coming off a career year at the plate, and he'd long earned praise as a clubhouse leader. It was in part because of that latter quality that the Padres -- beginning to emerge from a deep rebuild -- valued Hosmer. 

From this remove, there's no real way to gauge the positive effects of Hosmer's veteran guidance, but we can pass judgment on his statistical outputs now that we're almost a full season into his Padres contract. The results to date are not promising from the team standpoint.

At this writing, Hosmer this season is batting .250/.315/.395 with 17 home runs in 151 games. Even after you adjust for the run-suppressing effects of Petco Park -- those numbers yield a 96 ERA+ -- that's sub-par production for a first baseman. He's also carrying around a .300 batting average on balls in play, which suggests those depressed numbers aren't really the result of bad luck. His exit velocity is pretty much league average,  and his weight on-base average (wOBA, an all-encompassing advanced offensive statistic) is mostly in line with his expected wOBA. Again, he's been a below-average hitter for reasons other than simple misfortune. 

Two more reasons to worry: Hosmer is striking out at a career-high rate, and he's also showing the strongest ground-ball tendencies of his career. Striking out more often is an obvious concern in the absence of a power spike, but the latter trend is perhaps more worrisome. Hosmer has long been a ground-ball hitter, which isn't ideal for someone lacking plus speed and manning a power-first position. For his career, including 2018, he's got a ground-ball percentage of 54.2. This season, though, that figure has spiked above 60 percent for the first time in his career. Among 2018 qualifiers, only Ian Desmond of the Rockies has a higher ground-ball rate than Hosmer's 60.1 percent. 

For much of Hosmer's Royals career, we heard calls for him to focus on increasing his launch angle and tapping into his power. However, not much happened on that front -- Hosmer hit 25 home runs in 2016 and 2017, but that was mostly the result of higher homer rates on fly balls, not a decreased ground-ball percentage. This season, though, his disappointing production prompted him to make changes. Here's what Kevin Acee of the San Diego Union-Tribune wrote on Sept. 11 of this year: 

"I guess that's what we've been searching for all year," [Hosmer] said. "… It just got to the point where I wanted to focus on the main thing – 'What is the main thing of getting the ball in the air?' "

That's pretty much precisely what he asked hitting coach Matt Stairs and assistant hitting coach Johnny Washington before the series in Cincinnati.

It's not that Hosmer hadn't worked previously on getting the ball in the air. In fact, it had been a focus of his offseason.

But he figured the final month was the time to narrow it down.

Lo and behold, simplifying it to Stairs' advice to concern himself solely with the back leg — not his elbow or swing, typical instruments for manipulating launch angle — and timing his step more in sync with the pitcher's delivery.

In that series in Cincinnati, Hosmer homered three times in four games. Sure, the Reds' pitching and ballpark probably abetted that surge, but when a production spike coincides with mechanical changes we're inclined to think the player has unlocked something. 

Well, here's what Hosmer's done since the end of the Cincy series and since that piece was written:

  • .200/.273/.300 with two extra-base hits in 11 games;
  • 65.6 ground ball percentage and more than five times as many ground balls as fly balls. 

So since conferring with his hitting coaches and consciously undertaking swing alterations, Hosmer since that initial bust-out has been .... more ground ball-inclined than ever. That's troublesome, and it's a reminder that advocates of the "launch angle revolution" tend to oversimplify things. It's one thing to declare that hitters should just go out there and hit the ball in the air and do so with authority. It's another to do that in the face of muscle memory honed over the years and against the best pitchers in the world. Sure, guys like J.D. Martinez and Justin Turner have successfully remade themselves, but perhaps they're more outliers than models?

Insofar as the Padres are concerned, it's bad news that Hosmer has put up some of the worst numbers of his career, shown a greater proclivity for swinging and missing and putting the ball on the ground when he does make contact, and achieved nothing at the underlying level that allows us to dismiss it as an extended run of misfortune. He'll also be going into his age-29 season in 2019, so the relative youth that drove his market won't be in his favor all that much longer. 

Maybe over the winter, those swing changes will get a bit more sticky, and Hosmer will be able to drive the ball with more consistency. Recent results, though, suggests it's not all that simple, and the Padres may need to wrap their heads around the idea that Hosmer's value going forward is going to be driven by those human factors that have become part of his appeal. If this is his trajectory as a hitter, then he better be one heck of a clubhouse presence for the next seven years.