After a dismal bout of pitching and a disappointing 2025 regular season, the Arizona Diamondbacks entered 2026 with some clear need for improvement.

Following the conclusion of that 2025 season — which, ironically, ended with a playoff elimination in San Diego just as 2026 did — there was plenty of talk regarding Arizona's run prevention. Their rotation and bullpen had been largely ineffective.

But GM Mike Hazen specifically called out a different element of run prevention ahead of 2026. While acknowledging the need for strong pitching, he also pointed to Arizona's defense, which had faltered from one of MLB's best to middle of the pack.

Hazen intended to address that area, with the idea that better pitching results would also follow.

In 2026, that quickly turned around once again. With stronger defensive output and a better overall pitching impact, the Diamondbacks' run prevention soared to a much higher level during 2026.

Diamondbacks' defensive turnaround helped improve pitching results

The turnaround was drastic and notable. Arizona posted a Fielding Run Value of +34 in 2026, up from 14th to fifth in baseball with a total increase of +29. They tied for the second-fewest errors in baseball (64) and came in third in fielding percentage (.989).

On the Defensive Runs Saved front, they ranked seventh in baseball with +26. That number was a staggering -13 in 2025.

The Diamondbacks' defense has almost always been a strength since Torey Lovullo and Hazen arrived. It was a strange set of circumstances that erased that reputation in 2025, but Arizona returned to its defensive ways in 2026, and it made a serious impact.

How Diamondbacks turned defense around in 2026

One of the first steps Hazen took was trading for Nolan Arenado to secure a tough third base assignment.

The Platinum Glover and future Hall Of Fame infielder may not have posted his best-ever defensive season, but still held +2 Fielding Run Value and +2 Outs Above Average. He still made many a play that reminded fans of his days in a Rockies or Cardinals uniform.

But it wasn't just external additions. The Diamondbacks saw a breakout defensive performance from Geraldo Perdomo at shortstop, getting +13 FRV, +16 OAA and +8 DRS. That led to the franchise shortstop being named a finalist for an NL Gold Glove Award.

In fact, the D-backs got four Gold Glove-level seasons. In addition to Perdomo, Corbin Carroll (right field) Gabriel Moreno (catcher) and Ildemaro Vargas (utility) all had their names called as Gold Glove finalists. Ketel Marte had one of his better defensive seasons at second base, as well.

And even some of the D-backs' younger players saw defensive development through the course of 2025. Rookie outfielder Ryan Waldschmidt made large strides. Tommy Troy and Jordan Lawlar made quality outfield plays. Jose Fernandez showed flashes of defensive excellence at first and third.