Michael Mercado moves into Phillies’ rotation, will make first big-league start Tuesday at Wrigley

Rookie right-hander Michael Mercado will make the first start of his big-league career on Tuesday against the Chicago Cubs at Wrigley Field, Rob Thomson announced Saturday. Mercado was called up on June 23 and has only pitched one inning in relief for the Phillies, but he has plenty of minor league experience as a starter.

Zack Wheeler will pitch on Wednesday, and Cristopher Sánchez will pitch on Thursday. Thomson said he gave some thought to start Wheeler on Tuesday, so the Phillies could use Wheeler, Aaron Nola, and Ranger Suárez in the Phillies-Braves series next weekend. But Thomson wanted to give Wheeler and Sánchez an extra rest day.

“Yes, [I thought about it],” Thomson said. “But because of the 115 pitches [Wheeler threw] and then the complete game [by Sánchez], I think it’s just smarter to take care of those guys and give them an extra day.”

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Mercado had been stretched out to 90 pitches at triple-A Lehigh Valley. Thomson said it’s unlikely that he’ll push Mercado further than that. Mercado started the year as a reliever in triple A but transitioned into the starting rotation in early May. He posted a 1.98 ERA through 10 starts (41 innings pitched) for Lehigh Valley, with 39 strikeouts and 20 walks.

With Bryce Harper injuring his left hamstring in Thursday’s game, the Phillies now have had three hamstring strains over the last few months. Brandon Marsh was placed on the 10-day injured list with a right hamstring strain on June 3, and Trea Turner was placed on the injured list with a left hamstring strain on May 4.

Both Marsh and Turner are healthy now, but it is an odd coincidence — one that the Phillies medical staff and Thomson have looked into.

“Yes, we do postmortems basically on everything,” Thomson said. “[The trainers] do it, I do it myself. I go back and look at all of my paperwork and go, ‘OK, have I messed up here? Have I played them too many days in a row? Didn’t give them enough DH days?’ Or whatever it is. So we’re always checking ourselves to make sure that we’re doing what’s right and if we have to make adjustments, we do.

“At this point, it’s just coincidence, but they’re still grinding away at it.”

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Kyle Schwarber had only played two games in left field prior to Thursday night, and injured himself while trying to field a line single in the eighth inning. Schwarber is on the 10-day injured list with a left groin strain, but that won’t stop Thomson from playing him in left field — on occasion — when he’s back.

“No, I don’t think [that would change anything],” he said. “I think I’ll still use that spot to give other guys a half day, whenever I can.”

Right-handed reliever Luis Ortiz was placed on the injured list on March 31 with a left ankle sprain, and suffered a right forearm injury while he was on his rehab assignment. He will undergo Tommy John surgery on July 11, Thomson announced. … Thomson gave more insight into right-hander Andrew Painter’s workload on Saturday. He said Painter has been throwing 25-pitch bullpen sessions on Tuesdays and Fridays. He doesn’t expect Painter to finish the year with one of the Phillies’ minor league affiliates.