Mets put T.J. Rivera on DL, activate Neil Walker

SEATTLE -- The New York Mets have placed infielder T.J. Rivera on the 10-day disabled list with a partial tear of the ulnar collateral ligament in his right arm.

The Mets announced the move on Friday ahead of a three-game series in Seattle. New York activated infielder Neil Walker from the 10-day disabled list to take Rivera's spot. Walker has been out since mid-June with a hamstring injury.

The move with Rivera is retroactive to Thursday after he was unable to play in the series finale against San Diego due to the injury. Rivera has received a platelet-rich plasma injection in the elbow and will be re-examined in a couple of weeks to determine if surgery will be the best course of action.

Rivera was batting .290, fourth best among rookies in the National League.

Outfielder Brandon Nimmo was activated from the disabled list after being out since July 5 with a partially collapsed lung. Right-hander Tyler Pill was optioned to Triple-A Las Vegas.