Danny Valencia made his major-league debut in 2010, joining the Twins as a 25-year-old former 19th-round draft pick with a modest minor-league track record. He hit .311/.351/.448 in 85 games as a rookie to force his way into Minnesota’s plans, at which point he was handed the Opening Day job in 2011 and remained the starting third baseman all season. He quickly turned back into a pumpkin and by mid-2012 the Twins had tired of him on and off the field.

They traded Valencia to the Red Sox for a non-prospect and three months later the Red Sox sold him to the Orioles, who kept him for a year before sending him to the Royals for little in return. Six months later Valencia was traded from the Royals to the Blue Jays in a low-wattage swap and he was placed on waivers a year after that, when the A’s claimed him. Valencia changed teams five times in less than three years while spending much of that stretch in the minors.

He looked like the epitome of a replacement-level player. Not capable enough defensively to be trusted at third base, but not good enough offensively versus right-handers to warrant a full-time job at first base or designated hitter. Valencia was a 31-year-old platoon corner infielder with a reputation for too much … well, let’s call it swag. If anything, hanging around for as long as he did without being a former top prospect was a victory in itself. But then, just as it looked like Valencia might be running out of stops to make, he started crushing the ball.

It actually began in Toronto, where many a right-handed hitter has tapped into slugging potential few knew existed. In fact, the Blue Jays had such a logjam of right-handed, power-hitting corner bats that they viewed Valencia as expendable despite a .296/.331/.506 line in 58 games, and they lost him on waivers for nothing in return. He landed with the A’s and picked up right where he left off, hitting .284/.356/.530 in 47 games down the stretch. By the end of last season Valencia had been freed from platoon status and was starting every day at third base again.

Oakland bought into Valencia enough to make him the Opening Day third baseman this year and he hit cleanup against White Sox ace Chris Sale in the opener. He’s been the A’s best hitter this season, with only a brief disabled list stay for a hamstring injury interrupting his breakout. Since coming off the disabled list in early May he’s hit .378/.402/.720 with eight homers in 22 games. Dating back to the beginning of 2015—when Valencia was still in Toronto—he’s hit a combined .305/.355/.536 with 26 homers in 141 games to rank among the AL’s top 10 in AVG and OPS.

Part-time platoon players posting impressive-looking overall numbers is common, because by definition they are being placed in a position to succeed by facing primarily pitchers representing favorable matchups. And that’s how this Valencia train started rolling, but at this point he’s playing every day and has been for a while. Valencia was helpless against righties through his first five seasons, hitting a pathetic .226/.264/.351 in nearly 1,000 plate appearances. During the past two seasons he’s hit .295/.332/.526 off righties.

Valencia is one of just 19 right-handed hitters to post an OPS above .850 against right-handed pitchers since 2015. Nearly every other hitter on the list is a household name:

And then there’s Valencia, a 31-year-old journeyman on his sixth team in four years. He’s crushing lefties, he’s crushing righties, and he’s got an .891 OPS in his last 141 games. Mid-career breakouts aren’t unheard of, as evidenced by multiple players on the above list having one themselves. In this case, however, what Valencia has done stands out because many aspects of his overall game have not actually changed.

He’s still a butcher defensively at third base and he’s still a hacker at the plate—Valencia has drawn just 33 non-intentional walks in 520 plate appearances since 2015—but the mechanics of his swing bear little resemblance to the 2010 version. It does resemble the swings Encarnacion, Bautista, and other right-handed hitters found in Toronto. Valencia found it there too, but ironically the Blue Jays had so many useful right-handed hitters that they couldn’t find room for him long term.

Parker Hageman, who does great work breaking down swing mechanics for Twins Daily, shares my amazement at what Valencia has become after we both watched closely as he washed out in Minnesota. Hageman notes that the change in Valencia has been especially profound because he came up in a Twins organization that has long preached contact over power and a two-strike approach that emphasizes avoiding strikeouts. Those are considered bad habits in Toronto and the Blue Jays broke Valencia of them.

With the Blue Jays the emphasis is on getting the hands back, getting the bat on a flat plane, and letting it rip. “What happens, particularly with getting flat, is that the bat stays on plane and in the swing zone longer,” Hageman says. “They can swing hard and still have room for error, so if you get beat with a fastball you’re still able to drive it the other way.” As if right on cue for this article, Valencia went the other way for an opposite-field homer Tuesday against the Twins and then had three more hits versus his (original) former team Wednesday.

Compared to the 2010-2014 version, the 2015-2016 version of Valencia has increased his batting average on balls in play by 12 percent, his rate of “hard-hit” balls by 25 percent, and his isolated power by 61 percent. He’s also decreased his rate of “soft-hit” balls by 31 percent and his infield-fly-ball rate by 39 percent. Valencia’s strikeout rate has remained virtually identical—19 percent before, 20 percent after—but he’s making far better contact.

His two-strike results are vastly improved as well. Valencia posted a .499 OPS with two strikes from 2010-2014, totaling eight homers in 743 plate appearances. Since then he’s already totaled nine homers in just 251 plate appearances with two strikes on the way to a .695 OPS. When he was developing in the Twins’ farm system and spending his first three seasons in Minnesota he concentrated on putting the ball in play with two strikes. He no longer does that, because he’s too busy concentrating on hitting the ball over the fence on all counts.

Valencia’s average exit velocity of 93.8 miles per hour this season ranks 10th among American League hitters, one spot behind Blue Jays star and reigning MVP Josh Donaldson. Last season Valencia’s average exit velocity of 92.6 miles per hour also ranked 10th in the league, and two of the nine spots ahead of him were filled by Donaldson and Bautista. His swing looks noticeably different even to the untrained eye and the results are even more obvious, with harder-hit balls, more opposite-field power, and enough sustained production to think Valencia might be for real.

Toronto created a monster in Valencia. And, as tends to happen, that monster got loose.