Peterson, 30, was hitting .250/.332/.367 with six home runs and 11 doubles in 72 games with Triple-A Syracuse in the International League. He hit .296/.364/.531 with 25 home runs and 30 doubles in 122 games with Triple-A Memphis in the Pacific Coast League in 2013 in the Cardinals organization.
In a pair of stints with the Cardinals in 2013, his only time in the major leagues, the right-handed Peterson was 2-for-26 with two walks and 11 strikeouts in 23 games. He was drafted by the Twins in the 49th round in 2002.
Peterson is not on the 40-man roster, but if by chance he is added he does have two option years remaining, having only used an option with St. Louis in 2013.
Since Clint Robinson was promoted to the Dodgers, the Isotopes have started catcher Johnny Monell five times at first, with infielders Alex Liddi and Jamie Romak each also starting a game at the position.