Matt Cusick, 2b, Astros.
The next Ian Kinsler? Cusick was drafted last year out of USC; his 306/422/446 in the New York Penn League. This year, he is crushing the ball in the Sally League: 405/464/716. He was a hitter in college, but it seemed that there were questions because his tools aren't off the charts; from what I've gathered, loosely, he is a decent enough athlete to stay at 2nd. I would guess he gets bumped up to Hi-A if he keeps this up; if he continues to hit after the jump, I think he immediately pops onto the radar as a 2nd base prospect. Right now, he's a definite sleeper.
David Hernandez, SP, Orioles.
Coming into this year, this was a guy I and some others on this site identified as a sleeper; if I remember correctly, we chided John for giving him a C grade, as his peripherals, especially his k/9, pointed towards outstanding stuff the last two years. This year in AA, he seems to be putting it together: 37 k's in 25 innings, with a 2.52 ERA. His k/bb ratio is 37/14, and he has given up three homers in 25 innings. I'm not sure he can keep up that Bugs Bunny-esque k rate, but his track record suggests he's someone who can put up 9+ strikeouts per nine innings, at least in the minors.
Jeff Locke, SP, Braves.
A guy who got more attention coming into this year than Cusick and Hernandez, Locke's early starts have him sporting an ugly 5.63 ERA so far in 24 Sally league innings: but look at his peripherals: a 22/5 k/bb rate, and ZERO homers. Those early, ugly starts will be put in perspective soon, I bet, as his runs scored come back to match the rest of his periphs. I really think this guy is ready to make a jump as a top 50 prospect this year: great size, nice pedigree (2nd round pick), great organization, and a terrific track record so far.
Allen Craig, 3b, Cardinals.
The next Kevin Kouzmanoff? Hasn't had the injury problems Kouz had in the minors, but he seems to profile as a similar type hitter: really solid average and pop with just barely enough defense to stick at third. An 8th round pick in 2006, he hammered Hi-A pitching last year in the tough FSL league with a 312/370/530 line, and then made the late season jump to AA, putting up a 1.070 OPS in seven games. He got out of the gate pretty slowly this year, but seems to be coming around, hitting .357 in his last 10 games and going 253/343/391. I'd be shocked if he doesn't approximate his FSL line in AA by the end of the year.
Peter Bourjos, OF, Angels.
Like Locke, a pretty popular sleeper pick coming into this year; I've stated on this site before that I don't see much separation between Bourjos and Gorkys Hernandez as prospects. I thought he'd show more power (he's very toolsy), but I didn't anticipate the speed he's shown this year. So far in the Hi-A Cal league he's put up a nice leadoff line: 310/372/366 with 17 steals (and just one CS) in 18 games. He's also been described as Gary Pettis 2.0 defensively in CF; if he develops any power he becomes a really, really exciting prospect, but even if he doesn't he still looks like he could become a Gold Glove centerfielder with an above average OBP and lots of steals.
Ben Snyder, SP, Giants.
I know very little about this guy other than his size (6'2", 224) & stat line: 1.23 era and 23/4 k/bb ratio in 29 innings and 1 homer allowed in hi A. He went 16-5 with a 2.09 era last year in lo A, 145/32 k/bb rate in 151 innings.
Steve Garrison, SP, Padres.
Surprised when he made BA's SD top 10, as he doesn't have hot stuff, but his transition to AA has been superb: 1.59 era with a 13/5 k/bb ratio and no homers in 17 innings. The really curious thing is that he's only given up 9 hits in 17 innings, and just 2 hits in his last twelve innings. He can't keep that up, obviously, but I wonder what it is he does to keep hits down: he gave up just 32 hits in 42 Cal league innings last year with a 28/6 k/bb rate.