Chris Davis earned a seven-year, $161 million contract with the Orioles last offseason. Khris Davis was traded to the A's for a couple low-Minor League prospects. Chris Davis is a left-handed hitter and plays first base. Khris Davis is right-handed and plays the outfield. Chris Davis has been the best power hitter in baseball. Over the past three seasons, his .292 isolated slugging percentage is nearly 20 points higher than anyone else's, and he's hit 15 more homers than runner-up Nelson Cruz. Khris Davis has been a tantalizing, yet in many ways still flawed, player whose shine has somewhat faded after an explosive debut with Milwaukee in 2013.
Yet even with the flaws, namely his struggles with contact and plate discipline, one might be surprised to learn that Davis -- Khris, that is -- has also been one of the game's most prodigious power hitters, with an ISO that ranks in the top 10 since 2013. Since Khris came on the scene, he's hit for more power than Bryce Harper, Miguel Cabrera and Jose Abreu. Granted, injuries, defensive shortcomings and his one-dimensional nature at the plate have limited his playing time, and perhaps his power output isn't quite as impressive as his slugging peers who have done it for longer, but he's now batted more than 1,100 times and done so with an ISO that's indistinguishable from that of Paul Goldschmidt. The power is real, and just last year he took a step forward in one promising area to put his name alongside the game's premier power hitter -- the Chris with a C.
Chris with a C sure can pulverize a fastball. You can probably see the swing in your head -- the open stance, the uppercut, the flick of the wrists toward the fastball on the outside corner, the seemingly effortless motion that sends a low line drive hurtling over the left-field fence at Camden Yards. Chris makes homers look easy. He's got the kind of strength that makes hitting a fastball for a homer sometimes as simple as putting the bat on the ball.
When Chris with a C put the bat on a fastball last year, he did more damage than anyone. His .959 slugging percentage on contact against heaters was tops in baseball, more than 50 points above the guy in third place, and more than 100 points above the guy in fifth place. Nobody punishes fastballs quite like Chris with a C.
That hasn't always been the case for Khris with a K. Khris' swing is more violent, and it's led to inconsistent contact. Over his first two seasons, Davis slugged .691 on contact against fastballs, which is good but not elite, and with Khris' profile, the power needs to be elite for the whole package to be a real asset.
Gif: Khris Davis Home Run
Well, last year, something changed. Last year, Khris increased his slugging percentage on contact against fastballs by nearly 300 points. Nobody, not even born-again power hitter Matt Carpenter, improved the damage on fastballs more than Khris. He had the single largest increase in slugging against fastballs, and it catapulted him into some elite company:
Slugging percentage on contact vs. fastballs, 2015:

1. Chris Davis .959
   
2. Khris Davis .949
   
3. Bryce Harper .903
   
4. Mike Trout .890
   I know most lists like that would go five deep, but, c'mon, how fun is this four? It's the best power hitter in baseball, the two best overall players and the guy with the alternative spelling in his first name. If you can hit fastballs like Chris Davis, Bryce Harper and Mike Trout, you can be one hell of a hitter. Khris Davis got there.
   So what changed? It's hard to say. It could just be that he sold out a bit for more power. His contact rate dipped and his strikeout rate jumped, but so did the power. Maybe he's going all in. But "selling out" for power implies a negative connotation, and I don't think that's at all the case, because despite the added strikeouts, Davis last year improved his power and his on-base ability. It's the best pair of improvements you could hope for from any hitter, and in Davis' case, it seemingly all stems from pitch recognition.
   Davis' walk rate nearly doubled, and last year it ranked in the upper 25 percent of all hitters. He used to be the all-or-nothing slugger who doesn't take a walk, and pushing in all the chips for one skill is a risky proposition. Think of the walks like a safety net. Now, on the days when the thump isn't there, Davis can still make himself useful by getting on base. With the walks, he is a more well-rounded hitter.
   Davis is still aggressive, and he's still aggressive against fastballs. He's just done a better job of laying off the slow stuff:
   
   That's Davis' yearly swing rates, by pitch type. He stayed away from the breaking stuff after his rookie year. Then, Davis avoided the offspeed stuff. More of his swings now are going toward the fastball, and even those swings have improved.
   See, Davis lives for the inside fastball. He can get his hands around on it, and it's where he does the brunt of his damage. If it were up to Davis, every pitch would be on the inner half. Every pitch isn't on the inner-half, though, so he has taken matters into his own hands and put more of his swings on the inner half:
   
   The left side represents Davis' first two years. The right side is last year, when his swings became more focused on the inner half. Davis did a better job of attacking his pitch when he got it, and laying off the ones that weren't his.
   It looks like a picture of a more mature hitter, one who has harnessed his approach to maximize the opportunities for his freakish power to let itself be known. Davis is at his best when he gets the inside fastball, so he stopped swinging at the slow stuff, and he stopped swinging at the outside stuff. With more of his energy going toward the right kind of pitches, Khris Davis became Chris Davis against the heat.
   A version of this article first appeared at FanGraphs.com.