NEW YORK -- The Mets added four prospects to their 40-man roster Monday in order to protect them from the Rule 5 Draft, including one of the relievers they acquired during their midsummer flurry of trades.
The club protected right-handed pitchers Gerson Bautista, Tyler Bashlor and Corey Oswalt, and infielder Luis Guillorme, bringing the 40-man roster to 39 players.
Teams must add players who signed their first professional contracts at age 18 or younger within five Minor League seasons, or those who signed at 19 or older within four seasons, or they become eligible for other clubs to take in the Rule 5 Draft. Clubs pay $100,000 to make a Rule 5 selection, but if that player doesn't stay on his new organization's active roster for the entire next season, he must be offered back to his former club for $50,000.
Bautista, 22, was one of three pitchers the Mets acquired from the Red Sox for Addison Reed on July 31, along with Stephen Nogosek and Jamie Callahan. Appearing in 37 games overall in Class A ball, Bautista went 3-3 with nine saves and a 4.22 ERA. The Mets' 30th-ranked prospect according to MLBPipeline.com, Bautista struck out 73 batters in 59 2/3 innings.

Oswalt, 24, earned Double-A Eastern League Pitcher of the Year honors after going 12-5 with a league-leading 2.28 ERA in 24 starts for Binghamton. He finished second in the Eastern League in victories, third in WHIP (1.18) and fifth in opponents' batting average (.236), and is MLBPipeline.com's 27th-ranked Mets prospect.
Bashlor, 24, went 3-2 with 13 saves and a 3.44 ERA in 46 games split between Class A Advanced St. Lucie and Binghamton. He struck out 84 batters in 49 2/3 innings, a rate of 15.2 per nine.
Guillorme, 23, is the highest-ranked prospect the Mets protected, clocking in at 11th on MLBPipeline.com's list. An Eastern League All-Star and one of the organization's best defenders, Guillorme hit .283 for Binghamton and was the league's toughest player to strike out.