The Mets have signed outfielder Wily Mo Pena to a minor-league contract in order to add depth to their Triple-A club. Pena was released by the Nationals last month, and New York hopes he'll help invigorate their last-place affiliate.

The Nationals signed left-hander Ron Villone to a minor league contract on Friday, and he will pitch for Triple-A Syracuse. Villone, a 14-year veteran who has played for 11 Major League teams, is 56-59 with a 4.75 ERA during his career.

Tyler Walker has been signed to a minor league deal by the Philadelphia Phillies, reports Aaron Rowand to the San Francisco Chronicle. Walker was released by the Mariners near the end of Spring Training.

Pitcher Gustavo Chacin was released by the Nationals, and picked up by the defending-champion Phillies this week. The left-hander signed a minor league deal with Philadelphia.

Gary Sheffield has agreed to sign with the New York Mets, SI.com has learned. An official announcement is expected this afternoon. It is presumed that the Mets will pay him the pro-rated portion of the $400,000 minimum. The Tigers are obligated to pick up the rest of Sheffield's $14 million salary.