Straily, 27, is expected to open the season in the Padres bullpen, although he has been a starter for most of his career.
Straily is 13-13 with a 4.60 ERA in 52 games, 45 of them starts, with the Oakland Athletics, Chicago Cubs and Astros. He threw four no-hit innings Friday in a spring training game. He went 10-8 with a 3.96 ERA in 27 starts in 2013 as a rookie with the A's.
Kratz, 35, has hit .218 with 23 home runs in 192 games in the majors with Kansas City, Toronto and Philadelphia.