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Colby Thomas entered his second full professional season in the A’s organization having never played above High-A ball.

Less than three months later, he’s pushing for a big league callup.

Rated Oakland’s No. 11 prospect by MLB Pipeline, Thomas began his 2024 campaign at Double-A Midland. He dominated the Texas League by slashing .282/.340/.568 through 59 games with 14 home runs and leading all of Minor League Baseball with 36 extra-base hits. That strong start earned a promotion to Triple-A Las Vegas on June 18.

“It’s been fun to see him take the next step on his journey to the Major Leagues,” said A’s assistant general manager and director of player personnel Billy Owens. “Colby is electric. Tenacious motor accompanied by a high-caliber skill set. His sonic bat speed and abundance of strength make him a threat every plate appearance. It’s noticeable how he plays with an edge and controlled aggressiveness every time he steps on the diamond.”

The success has quickly carried over to Triple-A. Through his first 10 games with Las Vegas, the 23-year-old outfielder is 12-for-41 (.293) with five doubles and one homer.

Thomas is proving to be a stellar hitter at each level, but that is just one of his many plus tools. The A’s have also been impressed with his defense, ability to play all three positions, good arm and solid speed; he’s 12-for-13 in steal attempts this season.

“He’s been nothing but great since he’s come up from Double-A,” Triple-A Las Vegas manager Fran Riordan said on A’s Cast. “It was a deserved callup. … He’s a great runner. He’s continued to hit since he’s been here. He’s a very strong kid. He’s got a nice swing and a good approach.

“He knows what he wants to do when he gets in that batter's box. He’s a good defender in the outfield who can play all three positions, and he’s got enough arm. Definitely enough speed. The way he plays, it’s kind of an old school, ‘I’m just going to play as hard as I can for as long as I can and not give anything away.’ That’s kind of how he approaches every game, every at-bat and every defensive inning.”

Thomas has done nothing to suggest he can’t have success at the Major League level. All that is left for him now is to continue getting reps at Las Vegas, see how pitchers adjust to him – which, to this point, has proven mostly futile – and polish his approach at the plate.

If he keeps up this performance, you can expect to see Thomas patrolling the outfield in Oakland at some point in the second half of the season.

“I think he’s going to be a really good big leaguer,” Riordan said. “Just like 99.9 percent of the playing population, you have to go to the next level and prove it in a decent sample size that you’re ready to go to that next level. Being put in positions to make the adjustments necessary when the league starts to see what you do and who you are is very important. So far, Colby has done a very good job of that.”

Thomas is our pick for the A’s top-performing prospect in the first half. Here are more selections from the club’s three other full-season affiliates:

Double-A Midland: RHP Gunnar Hoglund (A’s No. 16 prospect)

Double-A stats: 3.08 ERA, 1.10 WHIP, 79 strikeouts and 25 walks over 84 2/3 innings in 15 games (14 starts)

The lone player remaining from the Matt Chapman deal with Toronto in 2022, Hoglund is finally in a good place with his health after being injured for the majority of his A’s career. Pitching with a bit more freedom after he was on a strict innings limit in 2023, the 24-year-old right-hander has pitched into the sixth inning in 10 of his 14 starts.

High-A Lansing: OF Henry Bolte (A’s No. 10 prospect)

High-A stats: .276/.393/.510 with 18 doubles, 11 homers, five triples and 51 RBIs in 68 games

Bolte is thriving in his first taste of the Midwest League as a 20-year-old, leading the Lugnuts in OPS (.903), homers, extra-base hits and RBIs. Beyond the numbers, the A’s have been impressed with his ability to soak in information and make adjustments when necessary.

Single-A Stockton: 1B Luke Mann (unranked, now in Lansing)

Combined stats: .285/.367/.475 with 12 doubles, 10 homers, two triples and 37 RBIs in 63 games

Mann flew under the radar a bit as a 14th-round pick in last year’s MLB Draft out of University of Missouri. His strong start at Stockton earned him a promotion to High-A Lansing, where he continues swinging it well by hitting .265 through 23 games.

“He’s a professional hitter with some versatility,” Owens said of Mann. “He does damage with his bat and is an effective defender. I see some Mike Moustakas attributes to his game.”