Pitching and Defense Have Failed the Diamondbacks

The Arizona Diamondbacks' season appears to be spiraling out of control. They are 27-30 and have lost eight of their last nine games. They are 5.0 games out of the Wild Card with five teams in front of them. Coming into the season with such high expectations, it's difficult to fathom at times how they got here.

The D-backs are fifth in Major League Baseball in runs scored per game, averaging 5.02. They are tied for the third-most games scoring 6 or more runs with 23. When teams in Major League Baseball score six or more runs, they're supposed to win that game. So far in 2025 teams are 424-77 when scoring six or more, which is an .846 win percentage.

Yet the Diamondbacks are just 13-10 in those games, a .565 win percentage. That is the second-worst in MLB, above only the Colorado Rockies, and Arizona's 10 losses are twice as many as any other team.

It's true that the D-backs have lagged behind in batting average with runners in scoring position this year, but they've still scored plenty of runs, enough to have a much better record than they currently hold.

If they were simply average in winning games with six or more runs, they would be 19-4, improving their record by six wins. Instead of being 27-30 they'd be 33-24, which would put them right in the third NL Wild Card spot.

The issue is a failure in run prevention. When it comes to allowing runs, Arizona is among the worst in the league, giving up 5.16 per game, which ranks 26th. While the bullpen has taken the brunt of the criticism, in reality there is plenty of blame to go around.

Depending on the day, or week, we tend to focus on the most recent failures — whether it be rotation, bullpen, or defense. That's the nature of recency bias. But taking the season as a whole and breaking it down in groupings makes things pretty clear.

Pitching and Defense Have Failed

Starting Pitching

The Diamondbacks' 4.33 starting pitcher's ERA ranks 25th in MLB. That number is inflated by Zac Gallen and Eduardo Rodríguez's struggles this year. Unfortunately, they've accounted for 35% of the starting pitcher innings. Their FIP numbers indicate some bad luck perhaps, while Corbin Burnes and Brandon Pfaadt are on the other end of the luck spectrum. But in total, this rotation has gotten pretty much what it's deserved when peripherals are taken into account.

Bullpen

The Diamondbacks' bullpen ERA is 5.51 and ranks 27th in MLB. That number was 3.48 through April 17 and they had not blown a save. A.J. Puk went on the Injured List April 18, and won't return before the end of June. Justin Martinez went through a dead arm phase and spent three weeks on the IL following that.

From April 18 onwards the bullpen ERA is 6.57, ranking 29th in MLB. The Win Probability Added, or WPA, is a stunning -4.54 during this span. Not only is that the worst in the league, it's more than twice as bad as the number 29 Los Angeles Angels, (-1.93). They've had 22 save opportunities and blown 11 of them.

The heroes of the 2023 Postseason run have imploded. Kevin Ginkel missed the first month of the season, and then pitched so poorly in 13 games after his return that he was optioned out to Triple-A Reno with a 12.60 ERA. Joe Mantiply pitched to a 15.83 ERA in 10 games and was recently designated for assignment. Ryan Thompson has been inconsistent and posted a 6.13 ERA in 22 games.

These are just some of the reliever problems. Shelby Miller has a 2.08 ERA, but due to some overuse and regression to the mean, he's give up six runs in his last nine games. Jalen Beeks was a savior, allowing just one earned run in his first 15 innings. But in his last 13.1 innings he's allowed 12 runs, 10 earned.

A host of other pitchers have come and gone, either being bounced out of the organization or demoted back to Reno. Few have helped, and there appears to be little relief in sight.

Defense

This has been perhaps the most mysterious problem. The Diamondbacks established their reputation as a strong defensive team in 2022, and that carried over into 2023. The defense was still above average in 2024, but not quite as sharp. Poorly-timed mistakes seemed to cost them games at times.

From the beginning of 2025, the team defense has been overall below average. But they've also been making mistakes at the most critical moments. During a recent press conference, manager Torey Lovullo said the front office analytics team showed him numbers indicating they were among the best in the league during innings one through six, but nearly the worst from inning seven onwards. Lovullo could not define exactly what metric he was referencing, however.

The table below was created by taking the average of Defensive Runs Saved (DRS) from Baseball Info Solutions that is published on Baseball Reference and FanGraphs, and then Fielding Run Value (FRV) from Statcast (also found on FanGraphs).

These numbers have shift (2022) and positioning runs stripped out, and the 2025 numbers are prorated to 162 games to make comparison easier.

Arizona Diamondbacks Fielding Runs | Jack Sommers

Comparing apples to apples, we can see significant deficits compared to past years at first base, second base, third base, and left field. All of that matches the eye test. Josh Naylor and Pavin Smith have both been below average. Naylor has been mistake-prone and Smith has poor range.

Ketel Marte has been a shadow of himself defensively due to leg problems, and the rookies that have filled in at the position — Tim Tawa and Jordan Lawlar — were mistake-prone. Eugenio Suárez has lost a step or two and has been mistake-prone as well. The same can be said for Lourdes Gurriel Jr.

Geraldo Perdomo has been above average, and Corbin Carroll has greatly improved, especially with his throwing. But in total this defensive unit has been a net negative and contributed greatly to the overall issue with run prevention.

Summary

Some have been blaming the coaching staff, but that does not appear to be a valid position. The pitching ranked 27th last year with Brent Strom as the pitching coach and is faring no better this year with Brian Kaplan.

Dave McKay is still one of the best outfield coaches in the game's history. It's not his fault that Gurriel has slowed down or that he's playing more innings in left than ever before. Gurriel hasn't DH'd once this year.

It's not Shaun Larkin's fault that Suárez and Marte have gotten older and slower. Nor is it his fault that he did not get to work with Christian Walker, hands-down the best defensive first baseman in the game since 2019.

Perhaps the mental lapses that have been happening are things that some might wish to hang on the coaching staff. But from this insider's view, these coaches drill and talk to the players on a daily basis, going over all scenarios and stressing fundamentals. If the players have tuned out the coaching staff, that's on the players, not the coaches.

If the Diamondbacks were simply average at run prevention, coupled with their offense, they would be breathing down the Dodgers' necks for the division lead. Instead, there are only four teams in the NL with a worse record.