With 34 games left in the season and their playoff odds dwindling, the Seattle Mariners are leaving no stone unturned. The reigning American League West champions will call up baseball’s top pitching prospect, left-hander Kade Anderson, to make his debut Saturday at home against the Chicago Cubs, a league source, speaking anonymously to discuss the unannounced move, confirmed to The Athletic’s Keith Law on Thursday.

Anderson, who ranks as The Athletic’s No. 1 prospect in Law’s updated list of top 70 prospects, was drafted a little over a year ago by Seattle out of LSU with the third pick.

Seattle has gone from leading the AL West to sitting 4 1/2 games behind the Houston Astros and three games back of one of the AL’s three wild-card spots. It last had possession of first place on July 20, when it sat 51-50 with a +21 run differential, the only positive run differential in the division. However, in the month since, the Mariners have gone from one game above .500 to eight games under .500 (60–68).

Losers of six of their past 10 games, the Mariners’ run differential on Thursday sat at -46, partly a byproduct of a 22-0 loss to the Milwaukee Brewers on Tuesday. At the start of play on Thursday, FanGraphs listed Seattle’s odds of making the postseason at 31.2 percent.

Pitching has been one of the biggest culprits for Seattle’s misery, with Mariners arms combining for a 5.56 ERA (4.75 by starters) since July 21. That 5.56 ERA ranks as the third-worst mark in baseball over that stretch, ahead of the Colorado Rockies and Athletics, two clubs without postseason aspirations.

Who should win NL MVP?

Joe Crisalli

Anderson, who is not on the Mariners’ 40-man roster, will have to be added before his debut. The most logical path is shifting right-hander Matt Brash to the 60-day IL to clear a spot.

After sitting out the remainder of the 2025 season following an extended amateur workload that ended with LSU winning its eighth national championship, Anderson made his professional debut in early April for Double-A Arkansas, having bypassed the lower levels of the minor leagues entirely.

In 18 starts, Anderson has posted a 1.06 ERA, striking out 135 batters with just 13 walks. That 1.06 figure is the lowest among any pitcher in the Texas League, with opponents slashing .147/.183/.216 against the 22-year-old. In all, Anderson has permitted 11 runs, five of which came in a May outing. He’s yet to permit more than two runs in his other 17 starts.

“It’s plus control and maybe plus command of a four-pitch mix highlighted by one of the minors’ best changeups, which has generated a 50 percent whiff rate when batters have swung at it and given him a reverse platoon split on the season,” Law wrote of Anderson in July.

Anderson earned the start for the AL in this year’s Futures Game, working a clean and efficient 10-pitch inning.

Keith Law’s take

Anderson ascended to the No. 1 spot in my rankings because he continued to show front-line stuff while exhibiting far better command and control than anyone expected — or than just about any college starter has shown in his pro debut in recent memory.

Anderson works with a four-pitch mix highlighted by an elite changeup that has generated a whiff rate of 48 percent this year, meaning that hitters have missed the pitch nearly half the time they’ve swung at it. He throws a slider and a true curveball, with the slider the better pitch, though both are missing bats at above-average rates so far. His four-seamer remains effective because he’s sitting in the mid-90s and has such good deception in the delivery.

His control has been otherworldly, with just a 3.9 percent walk rate this year that’s the fourth-lowest in any full-season league. Anderson has thrown 70 percent of his pitches for strikes this year, and he’s locating all three offspeed pitches exceptionally well. If he’s got a flaw, it’s that the fastball lacks much movement or life, and he’s going to have to get out of the heart of the zone against big-league hitters.

He looks like a future No. 1 starter, though I wouldn’t expect him to keep up a 1.06 ERA in the majors. Fun fact: He gave up five runs in one inning in his start on May 15, and has given up six runs total in the other 92 1/3 innings he’s pitched this year. — Keith Law