Why D-backs Rookie's Season Raised Serious First Base Concern

The Arizona Diamondbacks' rookie first baseman did not inspire much confidence in the position.

Aug 28, 2025; Milwaukee, Wisconsin, USA; Arizona Diamondbacks first baseman Tyler Locklear (28) reacts after getting hit by a pitch from Milwaukee Brewers starting pitcher Jose Quintana (not pictured) forcing in a run in the second inning at American Family Field. Mandatory Credit: Benny Sieu-Imagn Images | Benny Sieu-Imagn Images

It always takes more than the standard 26-player roster for an MLB club to make it through the marathon that is the 162-game season.

The Arizona Diamondbacks were no exception, with 65 different players making at least one appearance in the 2025 season.

Arizona Diamondbacks On SI will begin our player review series with a look at the D-backs' first base Deadline trade acquisition: rookie infielder Tyler Locklear.

For the purpose of these articles, we'll be using aWAR, an average of Baseball-Reference and FanGraphs WAR figures.

Locklear did not make much of an impact in a small sample size, but his struggles have raised concerns about the viability of Arizona's first base position long-term.

Related Content: D-backs First Base Future Depends on Unproven Player

Arizona Diamondbacks Player Review: Tyler Locklear

Tyler Locklear 2025 and career statistics. | Alex D'Agostino

Locklear was the primary return in the biggest Trade of Arizona's Deadline fire sale. The D-backs sent slugging All-Star third baseman Eugenio Suárez back to his former Seattle Mariners club in exchange for Locklear and a pair of pitching prospects.

Locklear was the biggest prize of that deal, at least in theory. Especially considering Arizona had just traded Josh Naylor to the same Mariners club a few days prior, the 24-year-old Locklear was expected to take at least a chunk of the D-backs' first base reps — if not an everyday role.

He'd been in the midst of an excellent season in Triple-A Tacoma for the Mariners, although the Pacific Coast League does always tend to inflate offensive numbers to a high degree.

But the rookie simply did not adjust well to MLB pitching in the 2025 season. He hit to just a .175 average and looked extremely uncomfortable at the plate, eventually being relegated to a heavy platoon alongside Pavin Smith.

Locklear found his way to three homers, but never performed enough offensively to inspire much confidence. Most concerning of all, he struck out 43 times against only 10 walks in his 31 major league games.

Toward the end of the season, Locklear suffered injuries to both his elbow and shoulder, ending his season prematurely. Both injuries required surgery, and his status for 2025 Opening Day is now in question.

What Tyler Locklear's 2025 Means for D-backs

Sep 7, 2025; Phoenix, Arizona, USA; Arizona Diamondbacks first baseman Tyler Locklear fields a ball for an out against the Boston Red Sox in the seventh inning at Chase Field. Mandatory Credit: Mark J. Rebilas-Imagn Images | Mark J. Rebilas-Imagn Images

There was some level of expectation Locklear would be ready to take on a larger role than he was eventually awarded in Naylor's absence. Not only did that not happen, but the D-backs' first base position was thrust into limbo after injuries to both Locklear and Smith.

Arizona's first base platoon posted an MLB-worst .560 OPS from August 1 onward. Eventually, the roster thinned out to a combination of Ildemaro Vargas and Tim Tawa at that position.

If Locklear was healthy and had more encouraging results in 2025, there might be some room for the D-backs to expect him to grow into the first base role. But as it stands, Arizona will need to address that position, adding another need to an already-lengthy list of offseason necessities.

If Locklear is able to turn a corner once recovered, Arizona's first base situation will be in a much more promising state. But as it stands, the rookie's 2025 season raises more questions than answers.