One problem you'll hear about last year's underachieving Chicago White Sox roster is that it was too heavy on the "stars-and-scrubs" model. Plenty of production came from guys like Chris Sale, Jose Quintana and Jose Abreu, but very little production came from the rest of the infield, the back end of the rotation and both corner outfield spots. This year's White Sox tried to fix that issue by adding guys like Todd Frazier, Brett Lawrie and Mat Latos over the offseason, and thanks to them as well as bounceback years from Melky Cabrera and Avisail Garcia, they entered play on Wednesday tied for the best record in the American League. 
Alongside the big guns, they've seen an increase in production from a player who was solid enough in his first two years in Chicago, but is now making the case to be tossed into the "star" category. I'm talking about Adam Eaton, who, going back a whole year now, has quietly been one of baseball's very best players.
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We talk a lot about sample sizes, particularly this early in the season. What can we take away from small samples? When is a sample large enough to draw meaningful conclusions? Certainly we're not far enough into 2016 to look at this year's results alone, but there's a nice little feature on the FanGraphs leaderboards that allows for "Past Calendar Year" split that helps with that. People are comfortable using full-season stats to evaluate players, and the Past Calendar Year split is is a different version of a full season's stats, where the arbitrary endpoints are less arbitrary. It's just "What have you done for me lately?" where "lately" is a full year, and everyone is on a similar playing-time scale.
We often use this feature throughout the season to sort of help mentally readjust perceptions of who the best players in baseball are "right now," for whatever that's worth. Something at the top of the leaderboard should immediately catch your eye:
Position-player WAR, past calendar year
1. Mike Trout, 9.5
2. Bryce Harper, 8.5
3. Josh Donaldson, 8.2
4. Manny Machado, 8.1
5. Yoenis Cespedes, 7.1
6. Kris Bryant, 6.7
7. Chris Davis, 6.4
8. Eaton, 6.3
9. Paul Goldschmidt, 6.2
10. Joey Votto, 6.2
Gif: Adam Eaton sliding catch vs. Oakland
You've got four guys who are viewed nearly unanimously as the four best in the world. You've got Cespedes, whose monster second half has carried over into 2016. You've got the reigning National League Rookie of the Year Award winner in Bryant, whose game has seemingly no holes, and you've got three of the most dangerous hitters in baseball in Davis, Goldschmidt and Votto. And then you've got Eaton, the 5-foot-8 outfielder, the entirety of whose "career highlights and awards" section of his Wikipedia page is "AL triples co-leader (2014)" and "Major League Baseball Defensive Player of the Month (April 2016)."
One of those things is not like the other, and yet there it is. Nothing is doctored about that leaderboard. According to the FanGraphs WAR model, Eaton has been one of the 10 most valuable position players in baseball for the past 162 games. Your first thought is probably how the defensive metrics have loved Eaton in right field this year, and how that's probably inflating his value. Except, the defensive metrics hated Eaton last year, in center, and Eaton agrees that he had a down year. The two almost entirely cancel each other out.
Eaton's elite WAR over the past year has not been inflated by defensive metrics. No, he's gone about achieving quiet superstar status the way some of his other elite peers have:

Guys like A.J. Pollock, Lorenzo Cain and Mookie Betts are probably still underrated by the casual fan, but are more often viewed as all-around stars within the game. Whatever reputation those three have, Eaton has earned the same.
Eaton is an average-to-plus defender in the outfield. He's a definite plus on the basepaths. Eaton hits at the top of the order and plays every day. But the most surprising thing about his ascension is the area where he probably doesn't get enough credit: he's turned into a truly great hitter.
That transition has likely been masked by Eaton's horrible start to last season, an April in which he hit .192/.241/.256. That April is now more than a year in the past, and since then, he's run a higher wRC+ than Bryant, Nolan Arenado and Matt Carpenter. Eaton credits a different weightlifting program than the one he used in Arizona for added strength. In the second half of last year, he started pulling more balls in the air to tap into that newfound strength. This year, Eaton has cut his strikeout rate in half, and is one of just 12 batters to have walked more than he's struck out. He talked in the spring about becoming a better situational hitter, with more contact. This year's contact rate hasn't changed from Eaton's career norms, but the strikeouts are way down. All of this suggests a change in swing, a change in approach, or both.
We can start with the swing. I went back about a calendar year and grabbed a couple of heat maps. The samples are close to equal. This simply shows Eaton's slugging percentage, broken down by zone, before May of last year, and then after May of last year:

Used to be that Eaton only did his damage on pitchers down the middle of the plate. Now, he's got a swing that can do damage on the outer-third of the plate, as well as the inner-third. Like any other hitter, he'll still make you pay down the middle, too. Eaton used to have a very particular swing, with plenty of holes. It's tough to find the hole in his swing nowadays.
There's also Eaton's changed two-strike approach, which has helped cut down on the strikeouts. Before 2016, he swung at 34 percent of non-two-strike pitches, and 64 percent of two-strike pitches. This year, the non-two-strike swing rate is similar, at 36 percent, but the two-strike swing rate is way up, at 74 percent. Eaton has become more aggressive with two strikes, trying to put the ball in play, and he's doing so with a swing that can now cover more of the plate.
Eaton hasn't radically changed his game at the plate, he's just improved across the board and turned himself from a good hitter to something better than that. Thanks to the well-rounded nature of his game, that improved bat's been enough to put him in the conversation with baseball's truly elite players going on a year now, and he only looks to be getting better. It's been subtle, but it's been real. Last year's stars-and-scrubs White Sox ditched the scrubs, and they may have quietly added another star.