It was a rough May for Diamondbacks starting pitcher Wade Miley. And that's probably putting it nicely.

The left-hander lost his fourth straight start and fifth of May on Friday, a 7-2 defeat against the Cubs, and despite a strong finish, the outing was enough for manager Kirk Gibson to put Miley on notice.

"I'm not going to let him go out and keep doing that," Gibson said. "It's a tough go when you're down six or seven to nothing."

Gibson had been asked if Miley might be able to carry some momentum from four scoreless innings into his next outing. The response: "He better."

After giving up a two-run home run to Alfonso Soriano in the first inning, a grand slam to Scott Hairston in the third inning and a solo home run to Cody Ransom two batters later, Miley had his third seven-runs-allowed performance in his last three starts.

In six May starts, Miley is 1-5 with a 7.34 ERA and more home runs allowed (seven) than in any month last season. After giving up seven runs on seven hits in seven innings Friday, Miley is 3-5 with a 5.01 ERA overall this year.

"I'm pretty frustrated, but you've got to take those last four innings," Miley said. "I feel like that's more me. I’ve got to move on from there and put all that other stuff behind me. I've got to quit thinking, get the mental stuff out of my head and go out there and compete."

The last four innings were undoubtedly impressive. After Ransom's home run, Miley retired 13 of 14 batters, only allowing a single. Perhaps more importantly, he spared a tired bullpen extra work after a taxing game Thursday.