PHOENIX -- The D-backs' starting rotation became a bit more clear on Monday after manager Torey Lovullo announced that Luke Weaver, who was expected to be one of the team's five starters, would open the season in the bullpen.

The rotation now appears to include Madison Bumgarner, Merrill Kelly, Zach Davies and Zac Gallen, with the fifth spot to be announced Tuesday morning. Caleb Smith, Humberto Castellanos and Corbin Martin are in the running to fill out the rotation.

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Weaver made two starts this spring. He allowed four runs with three walks and three hits over 1 1/3 innings in his first outing against the Angels, but he bounced back and surrendered just two hits and two walks over three shutout innings against the Padres on Thursday.

"I had that conversation with 'Weave' yesterday, and he took it very well," Lovullo said. "I don't think he was happy. I don't want to make it sound like it was perfect for him. He said, 'I am here to do whatever will help this team win.' So I thought it was a true team moment. He needs to just go out and pitch and execute and take the ball when we hand it to him, and go for as long as he can, as hard as he can."

When healthy, Weaver has been a part of the rotation in each of the last three seasons. He posted a 4.25 ERA with 62 strikeouts in 13 starts (65 2/3 innings) last year.

"We just felt like things were a little inconsistent from one inning to the next," Lovullo said when asked for the reasoning behind the move. "He's shown some good velo in his first inning and it would drop down in the second inning. I just felt like we would get the best version of him in small spurts for right now."