MLB trade grades: Mariners land Josh Naylor in first big deadline deal

It’s MLB trade season!

From the early deals to get things started to the last-minute rush of deadline day activity on Thursday, July 31, this is your one-stop shop for grades and analysis breaking down the details for every trade as they go down.

Follow along as ESPN MLB experts Bradford Doolittle and David Schoenfield evaluate and grade each move, with the most recent grades at the top. This story will continue to be updated, so turn back for the freshest deadline analysis.

Mariners get:
1B Josh Naylor

Diamondbacks get:
LHP Brandyn Garcia
RHP Ashton Izzi

Mariners grade: B+

This is the first significant trade heading into the final week before the deadline, and it’s interesting in part because it signifies the Diamondbacks are going to be dealing — Naylor could be the first of a group that might include Eugenio Suarez, Merrill Kelly and Zac Gallen, potentially spicing up the deadline with some intriguing names.

While third base was the Mariners’ biggest offensive need, Naylor gives them a well-rounded hitter who has been one of the top contact hitters in the majors this season, hitting .292/.360/.447 with 11 home runs and the 13th-lowest strikeout rate among qualified hitters. Naylor has done most of his damage against right-handed pitchers, hitting .310/.390/.493 with nine of his 11 home runs. That’s an upgrade over incumbent Luke Raley, who has hit .248/.370/.397 against right-handers but is just 1-for-20 against southpaws, with light-hitting Donovan Solano serving as his platoon partner.

Naylor can play every day and fits somewhere in the middle of the lineup, which ranks in the bottom 10 in the majors in strikeout rate, so his contact ability will be a nice addition. It also improves Seattle’s bench as Raley can now fill in at right field (although Dominic Canzone has been hitting well) or DH, with Jorge Polanco perhaps getting some time at second base over Cole Young. Rookie third baseman Ben Williamson is an excellent defender but has just one home run in 256 at-bats. While Polanco has plenty of experience at third in his career, he hasn’t started there since April 4 as a shoulder issue has limited his throwing.

In other words: The Mariners could still seek an upgrade at third base. The Diamondbacks might wait until July 31 to deal Suarez, hoping that one of the several teams that need a third baseman will give in with a nice package of prospects. The Mariners didn’t give up any of their top 10 prospects here, so here’s guessing that Seattle president of baseball operations Jerry Dipoto and Arizona general manager Mike Hazen aren’t done exchanging text messages.

Diamondbacks grade: B

While Garcia and Izzi didn’t rank in Kiley McDaniel’s top 10 Mariners prospects, that’s not necessarily a knock on their potential: Seattle’s top 10 is loaded with top-100 overall prospects. Garcia was ranked No. 13 on MLB.com’s team list and Izzi No. 16.

Drafted in the 11th round out of Texas A&M in 2023, Garcia was a surprising success story as a starter in 2024, but the Mariners moved him to the bullpen this season, and he just made his MLB debut after posting a 3.51 ERA across Double-A and Triple-A with 42 strikeouts in 33⅔ innings. He throws a mid-90s sinker along with a sweeper and cutter, and held lefties to a .235 average and .255 slugging percentage. He can probably go straight to Arizona’s bullpen right now, with the idea that the Diamondbacks try him as a starter in 2026. He’s a nice sleeper prospect in a trade like this, with at least a floor as a reliever and maybe some upside as a back-end starter.

Izzi is a 21-year-old righty with a mid-90s fastball who was a fourth-round pick out of high school in 2022, but he has struggled at high-A Everett with a 5.51 ERA across 12 starts. His fastball/sweeper combo could eventually work as a reliever, although right-handed batters have hit him as hard as lefties. He’s a development prospect.

Nothing too flashy here, but there wasn’t going to be a huge market for Naylor, and he was competing with the likes of Ryan O’Hearn and Marcell Ozuna in the 1B/DH class, so Arizona probably figured it had to strike first with Naylor, giving the team more time to discuss deals for their other pending free agents.