Mariners Acquire Josh Naylor from Diamondbacks: What to Make of Trade

Naylor has quick hands and easily catches up to fastballs. He’s hitting .328 off fastballs, including .303 (.485 SLG) against four-seamers.

The 28-year-old does chase often but he does have good eyes and puts bat to ball regularly, hence the strong 21.1% Whiff% on the year.

Naylor is a free agent after the 2025 season.

The Diamondbacks’ Return

• RP Brandyn Garcia (42 K, 3.51 ERA over 33.1 IP (AA and AAA))
• SP Ashton Izzi (54 K, 5.51 ERA over 47.1 IP (A+))

Arizona got back a Major League piece in reliever Brandyn Garcia. Garcia just made his MLB debut on July 21 and made two appearances for the Mariners before the trade.

Garcia’s a heavy ground-ball pitcher who excelled as a low-arm, hard-throwing reliever. The former Texas A&M product struck out 134 batters over 116 innings, almost all of which were as a starter. However, Seattle fast-tracked him as a reliever in 2025.

The 25-year-old fits the bill as a valuable left-handed reliever. He regularly hit 98-99 MPH with Tacoma, hitting 100 two times among tracked pitches. He’s primarily a three-pitch pitcher, with his heavy two-seamer, along with a slider and sweeper.

His 3.3” IVB on the sinker was over four inches better than the league average (7.6”) for left-handed pitchers.

The other piece in this deal is 6’3” right-hander pitcher Ashton Izzi, the Mariners’ fourth-round pick two years ago.

Izzi is a fastball/changeup/slider pitcher. The righty showed very good feel for the slider, with late action that broke away and to the left of same-sided hitters. And this season, Izzi showed more strikeouts in his game compared to 2024.

Last year, Izzi struck out 95 over 110.2 IP with Modesto (A). This year, the righty struck out 54 over 47.1 IP with Everett (A+), averaging over a strikeout per inning.

One thing to watch with Izzi is the command. The 21-year-old averaged almost five walks per inning last year and a 4.0 BB/9 in 2025.

Analysis

Oddly enough, this deal has some parallels with the Eugenio Suarez deal that occurred in November 2023. Aside from the fact that it’s been the same two teams, Arizona picked up a hard-throwing reliever in Garcia, albeit a left-handed arm.

Garcia should be a valuable pitcher for the Diamondbacks in the immediate future. With A.J. Puk sidelined through at least the end of 2025, and Justin Martinez out until at least mid-2026, the 25-year-old left-hander has the chance to play a key role in that bullpen.

However, Izzi — despite the Diamondbacks’ immediate need for starters at the MLB level — won’t be ready for at least another year.

As for the Mariners, Seattle was rumored to be willing to add more salary to bring in help. Naylor, on an expiring contract, should slide in nicely for a Mariners team that doesn’t have a big left-handed bat like Naylor, unless one counts switch-hitter Cal Raleigh.

Seattle tried the recently DFA’d Rowdy Tellez, while sprinkling in other options at first. Naylor should provide more stability and power to an infield that lacks it.