Hayhurst, 29, posted a 3.75 ERA with 7.5 K/9 and 1.9 BB/9 in 57 2/3 innings for the Blue Jays' Triple-A affiliate in 2009 before missing the '10 campaign to recover from right shoulder surgery. He has big league experience with the Padres and Blue Jays and is the author of the bestselling book The Baseball Gospels.
Mayora, 25, hit .286/.352/.440 for the Rockies' Double-A affiliate last year. He has considerable minor league experience at second and short and has played third as well.
Olmedo has spent parts of five seasons in the majors with the Reds and Blue Jays. The 29-year-old was last spotted in a big league uniform three seasons ago, but he has continued playing at Triple-A since. Last year, Olmedo posted a .284/.330/.387 line for the Brewers' Triple-A affiliate.
Bayliss last pitched in the majors for the 2007 Pirates. The 30-year-old spent last season with the Astros' Triple-A affiliate, where he posted a 3.58 ERA with 8.4 K/9 and 2.9 BB/9 in 65 1/3 innings.
Carter, who arrived in New York in the 2009 Billy Wagner trade, has big league experience in left and right field. The left-handed hitter posted a .263/.317/.389 line in 180 plate appearances last year. The Mets shielded him from southpaws in 2010; all but 7 of his plate appearances came against right-handed pitching.