CINCINNATI -- Given the uncommon situation of trading for a player whose old locker was just down the hallway, the Mets cleared immediate roster space Tuesday by placing third baseman Todd Frazier on the 10-day disabled list with a strained left hamstring. That allowed them to activate catcher Devin Mesoraco, whom they acquired for Matt Harvey prior to Tuesday's game against the Reds.
Frazier initially felt a twinge in his hamstring about three weeks ago, but had been playing through it without major issue. That changed in the eighth inning Monday, when he experienced more significant leg discomfort as he moved to field an Adam Duvall grounder. Frazier met with a doctor late Tuesday afternoon, and the Mets announced the DL move shortly thereafter.
"This is something I've never had before," said Frazier, who considers the strain minor and expects to be sidelined the minimum 10 days. "We've got to figure out a way to get better."
In 32 games for the Mets, Frazier is hitting .237 with five home runs and 21 RBIs.
Although the Mets did not immediately replace Frazier with another infielder, a source said the team plans to call up No. 10 prospect Luis Guillorme prior to Wednesday's series finale. A slick fielder who was batting .300 with an .828 OPS at Triple-A Las Vegas, Guillorme will be making his big league debut.
Working for the weekend
If there was any lingering doubt as to Jacob deGrom's health, the right-hander erased it with a sharp, two-inning simulated game Tuesday afternoon at Great American Ball Park. Warming up as he would for a regular game, then throwing 43 pitches over two "innings," deGrom did enough to prove to his superiors that his hyperextended right elbow is no longer an issue.

"Everything went better than we had expected," Mets manager Mickey Callaway said. "We all felt that he was going to be OK, but we wanted to make sure that we tested him in this way, where he could get out there and throw 100 percent."
Departing his last start in the fourth inning after injuring his elbow on a swing, deGrom was initially cleared to pitch Monday in Cincinnati. But the Mets later changed their minds, citing caution and a desire to see deGrom throw at full strength.
He did so Tuesday with third-base coach Glenn Sherlock standing in as a simulated batter, and will throw another, less intensive bullpen session Friday before coming off the DL on Sunday in Philadelphia.
"I feel like I'm good to go," deGrom said.
Roster move
P.J. Conlon's feel-good debut stint in the big leagues came to an expected end on Tuesday, when the Mets optioned him back to Triple-A Las Vegas to clear space for a fresh reliever. The team recalled right-hander Corey Oswalt, who will provide bullpen insurance until deGrom is eligible to come off the DL.

In his only big league appearance April 25, Oswalt limited the Cardinals to two runs over 4 2/3 relief innings. He would have been a candidate to start Monday had the Mets made a timelier decision to scratch deGrom. Instead, Conlon came up and allowed three runs over 3 2/3 innings, becoming the first Irish-born big leaguer since 1945.