Michael Mercado gets his chance to start for the Phillies with Spencer Turnbull on the injured list

On Monday night, shortly after he’d pitched seven strong innings in Detroit, Phillies pitcher Aaron Nola found a seat in the dugout, close to director of pitching Brian Kaplan. Twenty-five-year-old righty Michael Mercado was pitching the first big-league inning of his career, and Nola wanted a closer look.

“I just love watching guys make their debuts,” he said.

Mercado threw one inning with one strikeout, mixing his four-seam fastball, his curveball, and his cutter. Next week, he’ll make another debut, as a big league starter. It was not what Mercado nor the Phillies were expecting, but after starter Spencer Turnbull was placed on the 15-day injured list on Thursday with a right lat strain — with a return anywhere from six to eight weeks — it was the rookie who was next in line.

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Turnbull underwent testing on Thursday morning after exiting his start early on Wednesday. He had been moved into the rotation to replace Taijuan Walker, who was placed on the injured list on Sunday with right index finger inflammation. As a corresponding move for Turnbull, the Phillies recalled reliever Yunior Marte from Lehigh Valley.

In a way, Mercado was prepared for this. The Phillies used him as a starter and as a reliever in triple A this season. He wasn’t built up as much as some of the other starters at Lehigh Valley because he had only thrown 62 innings the year before. But he is stretched out enough to start. He had a 1.98 ERA in 10 starts for Lehigh Valley.

Kaplan said that the way Mercado was used in Lehigh Valley was less about a contingency plan for injuries to Turnbull and Walker than about giving Mercado an opportunity.

“We were trying to do what was best for him,” Kaplan said. “Watching him, listening to him work through his identity and who he is as a pitcher, the arsenal, everything, it just felt like starting fit him a little more naturally. And we wanted to give him that opportunity to continue seeking it.

“And it just so happened that he’s obviously had experience at high levels doing both now, and that helps us.”

Being thrown into one of the best rotations in baseball could be daunting for a young pitcher, but Kaplan is confident that Mercado has the maturity and poise to handle it. He saw it in his outing on Monday night. The righty threw 15 pitches, of which 11 were strikes. He attacked the batters and gradually increased his velocity as his outing went on.

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“Most guys come out and it’s like 100 mph off the backstop, but he was like, ‘I want to find the zone, and then add to it,’” Kaplan said. “That’s a piece of him that’s a little bit more mature.”

For Mercado to have success at this level, he will need to improve his control. He throws four pitches — a four-seam fastball, a cutter, a split-change, and a curveball — and throws hard — in the 95-97 mph range — but has historically allowed a lot of free passes and a lot of home runs.

He was able to drop his walk rate from 12.2% in 2023 to 11.9% this season and has drastically dropped his home run rate this year. Mercado allowed nine home runs in 39⅔ innings at triple A in 2023. He allowed just two in 47⅓ innings with Lehigh Valley this season.

These are positives signs for the Phillies. It’ll be up to the rookie to keep it up. He has the stuff to pitch in the big leagues, it’s just a matter of harnessing it.

Reliever Matt Strahm has seen it himself.

“He’s got electric stuff,” Strahm said. “I think our organization does a great job at the lower levels of instilling the belief of, ‘You’ve got great stuff, just throw it over the plate.’ As long as he stays over the plate with it … learning the hitters will come.”

Strahm has been a resource for Mercado since spring training. Like Strahm, Mercado is versatile. He could be used in any role at any time.

“[Strahm] told me that you just have to be ready for anything,” Mercado said. “I’ve gotten told plenty of times that I’m good enough to be a starter in the big leagues; you just have to have the confidence that you’re better than the guy you’re facing. Because if you don’t have that, I don’t think good things are going to happen.”

Mercado didn’t always have this confidence, but he’s done a lot of work with mental skills coaches, and with Kaplan, to build that side of his game. It’s something that will come into play now, as he embarks on a new challenge.

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“He’s steady,” Kaplan said. “He’s just really steady. He doesn’t seem to have a lot of self doubt. He doesn’t seem to get anxious or overly excited about a situation. Just seems to have a really steady hand. It’s easy him for him to stay focused.”

A few weeks ago, when Mercado was still in triple A, the rookie explained why it’s easy for him to do that.

“I do my best to be the same person, whether I have 1.00 ERA or a 7.00 ERA,” he said. “We have a mental skills coach that is there with us probably 75% of the time, and I always tell him, I try to be able to separate me, as a person. Baseball is not what defines me. It’s just something that I do, and if it’s going well, then great, and if it’s not, then it’s just another challenge for me.”

There is not much depth behind Mercado at the moment. Manager Rob Thomson mentioned Tyler Phillips and David Buchanan as options in Lehigh Valley. Kolby Allard is an option, too. Phillips, who graduated from Bishop Eustace Prep, has a 5.02 ERA in 14 starts. Allard has a 6.37 ERA in six starts, but a 2.49 ERA over his last four.

Buchanan has a 5.19 ERA through 10 starts.

Walker has no timeline for a return yet. Thomson said he is doing weighted ball exercises to build velocity and is playing catch.

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For now, the plan is for Mercado to start sometime after Monday’s off day, but Thomson didn’t specify when. Mercado will be used out of the bullpen on Thursday and Friday and move to the rotation after that. The biggest adjustment, according to Kaplan, will be shifting him to a five or six-day workload.

The All-Star break should help with that. Mercado likely will have two starts before the July 16 All-Star Game.