Who's the real Eric Hosmer?

If we look at only the past 30 days, which, to be fair, is still a small sample size when evaluating players, it's not at all surprising to find that the Orioles' Chris Davis, who leads baseball with 33 home runs, has been the No. 1 first baseman in fantasy, according to the ESPN Player Rater. It might surprise you, however, to learn that over those same 30 days, Eric Hosmer not only ranked No. 2 among first basemen, but also in the top 10 overall, hitting .320 with eight homers, 22 RBIs and a 12-to-9 strikeout-to-walk ratio.

To put this in proper perspective, remember that Hosmer was barely ownable in mixed leagues of any size for the first couple months of the season. After all, he batted just .261 in April and May combined, struck out twice as much as he walked and hit just one measly homer in his first 61 games.

Which raises this question: Just how seriously should fantasy owners be taking this recent power surge from the Kansas City first baseman?

Well, let's start with the hiring of Royals legend George Brett, who was brought on as the team's new hitting coach on May 30. Perhaps it's more anecdotal than anything, but we can't ignore the fact that Hosmer's jump in production lines up rather well with Brett's arrival. According to a recent story in the Kansas City Star, Brett worked with Hosmer on moving his hands back slightly in his stance so he didn't have to shift them back as part of his swing. This shortened Hosmer's swing and allowed him to get his bat to the ball more quickly.

It's hard to say for certain that Hosmer's recent uptick is largely the result of Brett's coaching and the new mechanical adjustment, but on the surface, the splits do look significant. In 190 plate appearances before Brett's arrival, Hosmer batted .262/.323/.331 with only one home run. Since Brett took over, the 23-year-old has hit .318/.355/.552 with eight home runs in just 166 plate appearances. In short, he has gone from waiver-wire fodder to a must-start option, even in shallow mixed leagues.

In addition to Hosmer's turnaround since the Brett hiring, the former first-round pick has made some other strides this season, most notably an improved contact rate. Not only is Hosmer's 85 percent contact rate so far this year a career best (and more in line with his 84 percent contact rate in 2011, when he batted .293 with 19 homers in just 128 games), but it has improved every month this season, which is a good sign for his batting average.

March/April: 75 percent of at-bats
May: 87 percent
June: 88 percent
July: 93 percent

It's also worth noting that Hosmer, a lefty hitter, has struggled against left-handed pitchers in the past. In 2011, he posted a slash line of .237/.282/.303 in 152 at-bats against southpaws, and last year he hit just .220/.284/.308 in 182 at-bats against them. This season, however, he has turned the tables. While only one of his nine homers has come against a lefty, he's batting .333with a .370 OBP against them in 89 at-bats.

In other words, even with the relatively small sample size, there are some signs here that suggest Hosmer has turned the corner after a disappointing 2012 campaign and an excruciatingly slow start to this season. What I still find troubling, however, is that the main issue that plagued Hosmer last season, when he batted just .235/.304/.359 in 152 games and finished as the 35th-best first baseman on the Player Rater, is still present this season. In fact, it's worse now than ever before.

Hosmer's primary issue in 2012 was his propensity to hit the ball on the ground. A high ground ball rate is fine for a player who relies on his wheels to get on base, but it's troublesome for corner infielders who are counted on to hit for power and produce runs. Last season Hosmer sported a 53.6 percent ground ball rate, tying with speedster Michael Bourn as the 11th-highest mark in baseball. In 2013, Hosmer's ground ball rate has actually increased to 56.5. That's the sixth-highest mark in baseball, just behind Everth Cabrera and Jean Segura, who, unlike Hosmer, rely on their speed as a big part of their games (they currently rank first and third, respectively, in stolen bases in the National League).

Only one player over the past two seasons has posted a ground ball rate of at least 55 percent and hit more than 11 home runs (Derek Jeter with 15 last year). Hosmer already has nine this season, and the way he's going, he shouldn't have trouble eclipsing that mark. But Hosmer's HR/FB rate over the past month, during which time he has clubbed seven of his nine home runs, sits at 28 percent. That mark is likely unsustainable over the remainder of the season. In fact, only one player in the past four years -- Adam Dunn in 2012 -- has held a HR/FB rate better than 27 percent for an entire campaign. When the inflated HR/FB rate from Hosmer's recent hot streak regresses, his home run total is going to suffer; he just hits way too many ground balls to be a consistent source of power. And with middling power in the first place, Hosmer's ceiling is only so high.

Even when the power outburst we've seen from Hosmer over the past few weeks drops off as expected, there is still a good amount of value here. For one, he's on pace to steal double-digit bases for the third straight season, which is a rare and valuable attribute for a first baseman. And in addition to being a ground ball hitter (which actually helps in the batting average department, as ground balls are more likely than fly balls to go for hits), Hosmer boasts a career-best 22.4 line-drive rate this season, which, if it continues, will help him post a good batting average.

For the season, Hosmer ranks just 13th among first baseman on the Player Rater (though, to be fair, this includes Buster Posey and Matt Carpenter, who are used at other positions in the majority of leagues) and 56th among all hitters. That's not a great fantasy option, but it's a productive one, and one that deserves to be owned, even in 10-team standard leagues.

Verdict: I'm not buying that this is the beginning of a true breakout for Hosmer, as his production over the past few weeks might suggest. Yes, he's still just 23 years old and was a former third pick overall (in the 2008 MLB draft), so improvement can be expected. Perhaps Brett's instruction really has helped him take a step forward. But don't mistake this hot streak as a buying opportunity for a guy you feel will be a difference-maker in the second half. Hosmer could provide that kind of fantasy value in future seasons, but he doesn't profile as that type of hitter right now. Simply put, at this point in time, he's still more James Loney than Joey Votto.