So how has Davis turned from Babe Ruth into Mark Reynolds overnight? As is usually the case in these scenarios, the BABiP of the slumping player in question has taken a major nosedive. It's at .250 right now, 74 points below his career average and 86 points less than what it was last year. Given that his line drive rate is over 26 percent--a career-best--Davis appears to be suffering from horrible luck this year. It doesn't help that like most lefthanded pull hitters, he faces defensive shifts on a regular basis. Based on his .145 average on ground balls (.199 last year), it would seem Davis has lost more than a few base knocks to these strategic alignments.
The sharp downturn in BABiP fully explains why his batting average is down almost 90 points from last year. That's not the only thing that jumps out from his batted ball data, though. He's also showing slight dips in his fly ball rate, from 45.7 percent last year to 40.3 percent this year, and home run/fly ball rate, from almost 30 percent to just a shade under 23 percent. The latter is likely a result of normal regression to the mean, as it's very difficult to hit three fly balls out of the yard for every ten put in play.
So bad luck combined with aggressive defenses and normal regression--all factors outside of one's control--have combined to put a hurt on Davis, but the simple truth is that he hasn't the same hitter he was in 2013. Less complete, less dangerous. Where he's really struggled is against offspeed pitches and breaking stuff, as Jeff Sullivan of FanGraphs points out here. Davis has more or less been the same hitter he was against fastballs as he was last year, but this year he's been a mess against non-heaters. Pitchers have exploited this weakness, throwing him fewer fastballs in favor of more curves and changeups, against which Davis has been helpless.
All that flailing has led to the second-worst worst contact rate and strikeout rate of his career. It also doesn't help that he's seeing more first pitch strikes than he did last year, causing him to fall behind early in the count (never good for a big-swinger such as Davis). He's been more selective, which should be a good thing, but based on the previous fact it seems that his discipline may be working against him, especially when he lets those first pitch fastballs go by. It's good to see him laying off more balls, but it would probably serve him well to be more aggressive against pitches in the zone, particularly early in the count when he's more likely to see a fastball. After that, he's going to see more breaking and offspead stuff used to put him away.
(I also might as well bring up the fact that Davis spent time on the Disabled List earlier in the season with an abdominal strain. Before going on the DL his OPS was .754; since returning, it's .688.)
Is there any hope for Davis, whose numbers have declined every month since May? Well for all his struggles, he continues to do what he's always done best: hit for power. With six home runs over the last month and 19 on the season, he's still on pace for around 30 homers and 80-85 RBI--essentially a repeat of his 33-85 production two years ago. With a playable on-base percentage over .300 (which should only improve as his luck turns), there's a regular spot for him in Baltimore's lineup. Just not in the middle of it.