The Arizona Diamondbacks are heading to Coors Field for the first time this season, and as any baseball fan knows, games in Denver are never straightforward. No lead is ever truly safe, and bullpens often leave the Mile High City battered and bruised. But there's reason for optimism in the desert: the D-backs' relief corps has been nothing short of stellar in May.

In fact, the numbers are startling. Arizona boasts the lowest bullpen ERA in the majors this month, allowing just seven earned runs—and three of those came in a single outing from Paul Sewald in Texas. Sure, they've also logged the fewest relief innings, but that's a testament to the starting rotation finding its groove after manager Torey Lovullo's much-needed meeting in Chicago. The starters are going deeper into games, meaning the bullpen is only needed for about 2.2 innings per contest. Compare that to the Detroit Tigers, who have leaned on their relievers for a staggering 63.1 innings—more than five per game. That kind of workload can wear down even the best arms, but for now, Arizona's staff is fresh and ready.

The real test, however, will come over these three days at altitude. Coors Field has always been a different beast for visiting teams, and the Rockies are a tougher out at home (8-11) than on the road (9-16). The gap in win percentage between home and away is a whopping 171 points—nearly double what it was in 2025. All eyes will also be on Nolan Arenado, making his first return to Denver since being traded to an NL West rival. His departure seemed to curse the Rockies, who have since posted the worst record in baseball by a wide margin. As the D-backs look to keep their bullpen streak alive, expect a hard-fought series under the lights at Coors.