Top Waiver Wire Adds: August 21st, 2026

Kade Anderson, SP, Mariners

There may not be a more hyped waiver-wire arm all season than Anderson, who makes his MLB debut this Saturday against the Cubs. The Mariners took him third overall in last summer's draft after he led LSU to a national championship and won College World Series Most Outstanding Player, and he wasted no time validating the pick, posting a preposterous 1.06 ERA with 135 strikeouts against just 13 walks over 93⅓ innings at Double-A Arkansas. That works out to a 13.7 K/9 and a 10.4 K/BB ratio — command numbers that are almost unheard of paired with that kind of swing-and-miss stuff.

The arsenal is four pitches deep: a fastball that sits 92-94 mph and touches 97, a classic curveball, a sharp slider, and a fading changeup, with his command the separator beyond the raw stuff. Seattle has a track record of trusting arms who never pitched above Double-A — Bryan Woo and Bryce Miller both broke out that way — and with the M's fading in the Wild Card race, there's real urgency behind the call-up. He'll also retain rookie eligibility for 2026, making him a legitimate AL Rookie of the Year threat. Expect big things out of fbaseballs number 4 overall prospect.

Trent Grisham, OF, Yankees

Grisham has quietly been one of the hottest hitters in baseball over the past couple of weeks. He's riding a stretch that includes a 10-for-21 five-game run with four homers and eight RBI, a two-homer, four-RBI game against the Mariners, and — most recently — a game where he drove in all three Yankees runs in a win over Baltimore. For the season he's now up to .225/.314/.418 with 17 home runs, 54 RBI, seven steals, and 61 runs through 399 plate appearances, hitting near the top of a dangerous Yankees lineup.

The batting average will always be the drag on this profile — he's a career sub-.240 hitter — but the power/speed combination is real, and he's shown it before: last year he set career highs across the board with 34 homers, an .812 OPS, 74 RBI, and 87 runs, backed by a strong 46.4% hard-hit rate and a healthy barrel rate. Hitting leadoff in front of Judge and company gives him plenty of runs-scored opportunities, and the current surge looks like a legitimate return to that form rather than a one-week fluke.

Kodai Senga, RP, Mets

Senga's season was a disaster right up until the Mets moved him to high-leverage relief — and now he's turned into a real source of saves. After the club placed struggling closer Devin Williams on the IL with a shoulder strain, Senga picked up his first career save against Atlanta, hitting 99 mph and using his signature "ghost fork" to strike out the side. He's followed that up with more clean save chances, including finishing off a sweep of the Nationals, and across his five outings in the ninth inning he's allowed just one hit and two walks over five scoreless innings with seven strikeouts.

The season-long ERA (7.82) is ugly and reflects his brutal run as a starter, so don't be scared off by the box score line — this is purely about the role right now. Interim manager Andy Green has praised how quickly Senga has adjusted to closing games, and with the Mets out of playoff contention and no clear alternative in that bullpen, he looks like the primary closer for the rest of the season, even as questions linger about back-to-back availability.