T.J. Rivera to DL with partial UCL tear

SEATTLE -- T.J. Rivera's breakout with the Mets took a major blow Friday, when doctors diagnosed him with a partial tear of the ulnar collateral ligament in his right elbow. Though the Mets are hopeful Rivera can avoid Tommy John surgery, which would cost him most if not all of next season, they will not know for certain for several weeks.
The Mets gave Rivera a platelet-rich plasma injection and placed him on the 10-day disabled list prior to Friday's game against the Mariners, activating second baseman Neil Walker and outfielder Brandon Nimmo. The club optioned pitcher Tyler Pill to Triple-A Las Vegas to clear additional roster space.
"The injury certainly can be troublesome," manager Terry Collins said. "We'll just see how he comes out of it, get him back to doing some baseball activities, and see where he's at."
Rivera began sitting out earlier this week due to soreness in the elbow. Following the team's series with the Padres, he flew back to New York to be examined by Mets doctors, who made the diagnosis.
The Mets' hope is that the PRP injection, combined with a strengthening program, will allow Rivera to avoid surgery -- just as starting pitcher Seth Lugo did with a similar injury earlier this season. The task is theoretically easier for position players, who do not place as much stress on their arms as pitchers.
"If you strengthen the area, hopefully you can avoid any surgical procedures that pitchers go through," Collins said. "But until we see where he's at in a couple weeks, we won't know."
Still technically a rookie, Rivera is batting .290 with five home runs and a .760 OPS in 73 games, establishing himself as a solid right-handed option on the bench. A former undrafted free agent out of the Bronx, Rivera spent six seasons in the Minors before debuting last year at age 27.
"It's a tough break for him, but as I told him yesterday, he worked so hard to get here," Collins said. "Now that he's established himself as a big league player, it's a smart move to make sure he stays as healthy as he can. To get this injection is the first step to getting back on the field for him."
The move simplified the Mets' roster move for Walker, who had been on the DL since June 15 with a torn left hamstring. Though Walker played a game at third base during his rehab assignment to increase his versatility, he will serve as the Mets' starting second baseman for now.
"I felt comfortable earlier in my career moving around a little bit," said Walker, who hit .270 with nine home runs before landing on the DL. "Obviously I haven't had to do it for several years, but more than anything, it's about reps. So whatever scenario might arise, I'm going to try to be as prepared as possible for it. But as far as I know, I'm going to be ready to play second base until otherwise told."
Nimmo, who missed about a month due to a partially collapsed lung, will return to his role as a reserve outfielder and pinch-hitter. The Mets once again have four bench players and eight relievers in the bullpen.