Vargas, 34, spent 2012 with the Brewers' Triple-A affiliate in Nashville, posting a 7-1 record with a 3.69 ERA in 20 starts. In parts of eight Major League seasons, including 2003-04 with the Expos, he has gone 48-40 with one save and a 4.38 ERA in 217 games (114 starts).
Thompson played for the Angels and A's last season, going 0-1 with a 15.43 ERA in three games. The 28-year-old also made 46 relief appearances for Triple-A Sacramento (4-2, 3.34 ERA) while striking out 58 in 62 innings. He's appeared in 82 big league games (31 starts) over six Major League seasons, going 3-4 with a 4.21 ERA.
Perez made 10 appearances out of the Brewers' bullpen last season, going 0-1 with a 5.14 ERA. He has 42 career relief appearances (with Milwaukee, Philadelphia and Pittsburgh) and a 1-2 record and a 4.88 ERA.
Velez, 30, spent the 2012 season with Triple-A Memphis in the Cardinals' organization, batting .280 with 11 homers and 58 RBIs in 136 games. He has appeared in 259 Major League games over five seasons, batting .241 with eight homers and 72 total RBIs.
Jimenez made his Major League debut for the Mariners last seasons, going 1-for-17 in seven games. The 30-year-old hit .310 in 125 games for Triple-A Tacoma, with 32 doubles, 20 home runs and 81 RBIs.