Less than two weeks after missing out on a spot on the Seattle Mariners’ Opening Day roster, infielder Colt Emerson is in agreement with the M’s on an extension that would be the largest in history for any prospect yet to make his MLB debut, a league source confirmed to The Athletic’s Ken Rosenthal on Tuesday. Fansided’s Robert Murray was the first to report the deal.
The 20-year-old prospect’s deal would be for eight years and $95 million — $13 million more than the Milwaukee Brewers signed MLB top prospect Jackson Chourio for in 2023. Chourio’s eight-year, $82 million extension was the most lucrative contract offered to a player yet to debut in the majors at the time. Chourio was 19 and had barely played beyond Double A, where he totaled 128 games.
Emerson has even less high-level experience. The No. 22 in the 2023 draft sped through the Mariners’ farm system last year, playing 34 games in Double A and six in Triple A, to position himself this spring as a long-shot candidate to make the Mariners’ season-opening roster. He hit .268/.340/.488 with two homers in 47 plate appearances while playing strong defense at third base and shortstop. The team ultimately opted to send him back to Triple A one week before Opening Day.
Emerson, a product of John Glenn High in Ohio, made his pro debut shortly after becoming the Mariners’ top pick in 2023. He played in only 83 games in 2024, though, due to an oblique strain in April, a broken bone sustained when fouling a ball off his foot in May, and a hamstring strain during his time in the Arizona Fall League.
It may not be long before Emerson, who turns 21 in July, is given an opportunity to help the Mariners attempt to secure a second consecutive AL West title.
The No. 4 prospect on The Athletic’s Keith Law’s Top 100, Emerson started his 2026 season going 5-for-14 in three games for the Tacoma Rainiers. He smashed a two-run homer in the team’s first game, a 408-foot shot to the opposite field off a low-hanging first-pitch curveball in his second at-bat.
Wrote Law of Emerson’s hitting ability: “He has quick hands and generates plus bat speed, combining it with very advanced pitch recognition for his age, as he doesn’t chase much at all (22 percent in High A, where he spent most of last year) and picks up pitch types well already. He started the year putting the ball on the ground too often and appears to have dropped his hands just a little by year-end, with much lower ground-ball rates in Double A and Triple A, although he might want to drop them a little further to at least cement those gains in his line-drive rates.
“He really, really looks like he’s going to hit, both in the sense of making contact and hitting the ball hard enough to matter, and will do so while playing some position of value on the dirt. If he ends up at 20-plus homer power, which is probably his ceiling, he’s a superstar. Maybe he’ll hit .300-plus with enough secondary value in walks, doubles and defense to be a superstar even without a gaudy home run total. I’m not betting against him given how fast he’s moved and how hard he works.”
The agreement comes one day after the Brewers agreed to an extension with one of their top infield prospects who also has yet to make his major-league debut. Milwaukee and Cooper Pratt, No. 99 on Law’s preseason list, are closing in on an eight-year, $51 million deal.