The beginning of this season has not gone smoothly for David Peterson. He lost three of his first four starts, owning a 6.41 ERA over that stretch. After that, the Mets decided to switch things up. They began to use an opener before going to Peterson in bulk relief, a role he was used in during Sunday’s 5-1 loss against the Arizona Diamondbacks. Safe to say that role has resulted in better performances from him.

Peterson threw five strong innings, giving up three runs (all unearned) on four hits, while striking out three. He opened his outing with three scoreless innings, working around two errors. Then, things started to unravel in the bottom of the sixth. Ildemaro Vargas led the inning off by reaching base on a throwing error from Andy Ibáñez, his second error of the game. The Mets paid the price for that mistake, as the Diamondbacks would go on to score three runs in the inning. That effectively put the game out of reach.

Mandatory Credit: Ron Chenoy-Imagn Images

While Sunday went poorly from a team perspective, it was certainly a step in the right direction for Peterson. It was the first time he threw at least five innings since April 13 against the Los Angeles Dodgers. It was also the first time Peterson had an outing with no earned runs allowed since April 19 against the Chicago Cubs.

Moving forward, how will the Mets use him? Is there a scenario in which he returns to the rotation in a more traditional role? Or does it make sense not to mess with what is working for Peterson at the moment? This season’s numbers back up the latter. As a starter, Peterson is 0-4 with an 8.10 ERA across 23 1/3 innings. As a reliever, he is 1-0 with a 1.69 ERA across 16 innings. A significant difference, to say the least.

If you pull the curtain further back, there is more evidence in support of having an opener in front of Peterson. In the first inning this season, he has a 10.80 ERA. In the first three innings, Peterson has a 7.94 ERA. Opponents are having success against Peterson early in games. In comparison, he owns a 3.26 ERA in innings four through six. Peterson’s numbers have seen a major uptick as a bulk reliever. In the short term, this is a no-brainer. Peterson should continue to pitch behind an opener for the foreseeable future.