Historically, who played first base for the Diamondbacks?
Only seven players had 120-game seasons at first base for the Diamondbacks. The first five only reached that level for one season each. Following that, Paul Goldschmidt reached that level in 6 of 8 seasons. More recently, Christian Walker reached that level in 4 out of 6 seasons. In the last two seasons, no player reached 120 games.
This season, Ildemaro Vargas had the most games at first base (74 games). This season, he seemed to mostly share the position:
- April/May, shared with Jose Fernandez
- June, shared with Pavin Smith
- July/August, shared with Tim Tawa and Tyler Locklear
- September, shared with Tim Tawa and Pavin Smith
This season, the team Wins Above Average
(WAA) at first base was negative 2.4, which was comparable to last season’s WAA of negative 2.2. For more details about how bad things looked in July, see this AZ Snake Pit article.
And the offense was not much better. The following table shows, for first base, the team OBP and SLG (as well as the main players at first base).
Players who might play first base next season.
Current Diamondbacks.
Tim Tawa. In his second season in the Majors, Tim Tawa is no longer a dark horse. At 27 years old, he has not yet reached his peak performance.
“In 2026, his OPS improved every month [through August]. His OPS in August was better than league average. His defense was above average, especially at left field and first base.”
“Tim Tawa was one of four batters [in MLB] who were better than average on all five fundamental measures per Ben Clemens’ pocket guide (albeit he is basically an average batter).”
“He knows the mental imperative of expecting success while knowing it won’t always happen. He prepares for games with the mental skills staff and the hitting staff.”
“Tim Tawa is close to achieving everyday player status, which would exceed preseason expectations.” — Makakilo
Pavin Smith. After sharing first base playing time in June, Pavin Smith was designated for assignment in July. To my surprise, on 15 September he was back playing first base for the Diamondbacks. Upon his return, his 1.144 OPS was impressive (24 PAs). He is 30 years old. His salary is $2.25 Million. Next season will be his final in arbitration.
Current Diamondbacks who became FA at end of this season.
Ildemaro Vargas. His salary is roughly $1.4 Million. He is 35 years old.
At the end of last season, the Diamondbacks outrighted him off the roster. In December, they signed him to a minor league contract. On 23 March, they informed him that he will be on the active roster.
This season, his 27-game hit streak was the longest streak by a Diamondback in 27 years.
This season, in a series against the Athletics, he did something impressive and unusual.
“Ildemaro Vargas had a walk-off hit in Tuesday’s game during that series, and then ended up closing out (if not closing) Wednesday’s game from the mound, being called on to pitch with a 12-run lead.” — Jim McLennan
Current Diamondbacks in AAA, or who made their MLB debut this season.
Manuel Pena.
“Minor League Baseball today announced that Amarillo Sod Poodles infielder Manuel Pena has been named a Texas League All-Star at Third Base. The slugging infielder had a remarkable Double-A campaign that began on 0pening day with the Soddies until his promotion to Triple-A Reno on June 16.” – Amarillo Sod Poodles
“…, a promising player in AAA who could have a future at first base is Manuel Pena. He is 22.6 years old. Recently, he impressed two writers, in May and July.” — Makakilo
Jose Fernandez. He is 23 years old. This season, his MLB debut, he played half his games at third base and half his games at first base. He showed he can hit MLB caliber fast balls.
“…There’s little reason for a pitcher to risk the relative unknown placement of an offspeed or breaking pitch if he can simply power a pitch by the batter. Fernandez has definitively passed that test as he has walloped fastballs to the tune of a .364 BA and .500 SLG while still seeing them nearly 53% of the time….” — Ben Seigel
Current Diamondbacks who may need a defensive shift.
Ketel Marte. He is 32 years old. In 2026, his OPS+ fell from 147 to 107. Perhaps if he moved to a less demanding position, his batting would improve.
“Top prospect Demetrio Crisantes is knocking on the door after reaching Triple-A in July. With incumbent second baseman Ketel Marte signed through 2030, a defensive shift is likely coming at some point. The alternative to shifting Marte to first base would be to make him the full-time DH, but that creates a logjam in the outfield.” — Joel Reuter, 10 September, 2026
Possible Trade Acquisitions. Assuming the Diamondbacks pitching looks good for 2027, the Diamondbacks may look to acquire a first baseman. Avoiding the free agent market, I looked to acquire via trade (which is a strength of the Diamondbacks). I found two candidates.
Ryan O’Hearn. He is 33 years old, and under team control through the 2027 season. Although in 2026 his OPS+ fell from 127 to 108, he is a bounce-back possibility because his BABIP was down.
Andrew Vaughn. He is 28 years old, and under team control through the 2027 season. In 2026, his OPS+ rose from 99 to 130. His plate discipline broke out with career best 10.6 BB%, and 16.0 K%. While his squared-up percentage rose to a career high 33.9%, his hard-hit percentage fell to 43.5%.
How can these players be compared?
Let’s compare their OPS (with split against right-handed pitchers and left-handed pitchers) and let’s compare their defense on three metrics:
- Defensive Runs Saved (DRS).
- Outs Above Average (OAA).
- Defensive Fielding Run Value.
The following table compares the OPS of the candidates in 2026.
The following table compares the defense at first base of the candidates.
My View.
The best everyday player (no platoon) would be Andrew Vaughn.
Best spot player to be called up when needed would be Jose Fernandez (or Manuel Pena).
The best platoon players would be:
Vs RHP: Tim Tawa (or Ryan O’Hearn).
Vs LHP: Ildemaro Vargas (or Ketel Marte when his defense at second base declines).
