Next revision of the prospect list, this guy is gonna be on it. Peralta was signed along with the more-hyped Rolando Pascual in 2005, but pitched unimpressively as a 17-year-old in the Arizona League in 2006 before missing all of 2007 with Tommy John surgery. This year he's pitched well for Helena while serving mostly as their closer, posting a 36/8 K/BB in 29.3 innings; however, for 19-year-old kids in the low minors, scouting reports are just as important as numbers, and as Erik Miller and Nick Tyson have reported, Peralta has some serious stuff, namely a mid-90s fastball and a hard, late-breaking mid-80s slider.
I've been talking to Mike Newman, who runs the excellent Baseball Handyman, about Peralta, and I think Mike willl have a piece up on him tomorrow. Peralta is one to watch for sure.