Tyler Austin, 1B/OF, Yankees (Low-A Charleston)
A 13th-round pick in 2010 who signed for an above-slot figure of $130,000, Austin showed impressive offensive ability in the New York-Penn League last year; on a Sally League squad loaded with much more well-known prospects, it's Austin who has stood out, going 8-for-13 with three doubles, a triple and his third home run of the year. His season line is at .438/.471/1.031 after eight contests. He has nowhere near the tools of some of his Riverdog prospect brethren, but the bat stands out, and is very much for real.

Matt Barnes, RHP, Red Sox (Low-A Greenville)
Let's be clear about something: as an advanced pitcher who was a first-round pick out of a very good college program, Matt Barnes should be dominating Low-A hitters. He doesn't belong at this level, but that's out of his control and he's doing his best to get out of there: he has struck out 16 over ten shutout innings in his first two starts of the year, including seven over five one-hit innings on Friday. He's missing plenty of bats with a fastball that has been up to 97 mph in both starts, and while his curveball and changeup will be tested more at High-A Salem, he's seemingly ready for that challenge.

Wellington Castillo, C, Cubs (Triple-A Iowa)
The Cubs are not a very good baseball team, but they're not expected to be. This is a team in the nascent period of what will be a long rebuilding process. While Cubs fans seem preoccupied with what first baseman Anthony Rizzo and outfielder Brett Jackson are doing at Triple-A (and both are doing well), don't forget about Castillo, especially since regular catcher Geovany Soto is one of the club's better trade chips when it comes to building for the future. With three hits in all three of his games over the weekend—and home runs in two of them—Castillo is doing his best to make the front office more comfortable in jump-starting that rebuild.

Sean Doolittle, LHP, Athletics (High-A Stockton)
A supplemental first-round pick our of the University of Virginia in 2007, Doolittle began his career as a first baseman and occasional corner outfielder and was a solid prospect coming up, although hardly a top one: a .272/.354/.449 career average is respectable, but not enough considering his defensive limitations. His career as a position player came to and end after a pair of knee surgeries cost him two years, but the 25-year-old was a very good pitcher at a very good program and is trying to make his way back on the mound, and with impressive results so far. On Friday night Doolittle gave up two hits, but also struck out four of the eight batters he faced, and in 5.1 innings over three appearances so far, he has 11 whiffs and a perfect 0.00 ERA. Throwing harder than he did in college, Doolittle is parking his fastball comfortably at 93 mph while touching 95, while flashing a decent slider and changeup that still need refinement. All the Athletics can do at this point is keep testing him, but he's passed his initial challenges with flying colors and could be in Double-A soon.

Evan Gattis, C, Braves (High-A Lynchburg)
Gattis certainly has an interesting backstory. He gave up on baseball as an amateur but gave it another shot and was a 23rd-round pick in 2010 out of a D-II school in Texas. Almost 24 years old when selected, he's far behind in terms of the standard age and development curve, but he's certainly impressed with the bat; after hitting .322/.386/.601 at Low-A Rome last year, he's up to .469/.525/.844 in nine Carolina League games after going 5-for-6 with a double, home run and six RBI on Sunday. The Braves are in a bit of pickle with him, as at 25 he shouldn't be at this level, yet at Double-A the starting catcher is one of their top position prospects in 20-year-old Christian Bethancourt. The most logical move might be for Gattis to move up and move to first base, as he's a below-average catcher, and at his age, there's no time for a bat-ahead-of-glove player.

Billy Hamilton, SS, Reds (High-A Bakersfield)
Playing in Bakersfield is certainly going to help Hamilton's raw numbers, but there's still plenty to be positive about even with a more neutral approach to his statistics, as after a 7-for-10 weekend that included two triples, three walks, and of course three more stolen bases (giving him a minor league-leading nine), Hamilton is batting .382/.500/.676 in his first ten games. Playing in Bakersfield isn't going to help anyone steal bases, but Hamilton's speed is well-known. Bakersfield also isn't going to help anyone draw walks, and with seven walks, Hamilton's focus on his approach seems to be paying off. I've picked him as a dark horse for minor league player of the year honors before each of the past two seasons, as he continues to shine.

Mike Kickham, LHP, Giants (Double-A Richmond)
A sixth-round pick in 2011, Kickham ranked as the No. 9 Giants prospect entering the season, despite a 4.11 ERA in last year's full-season debut at Low-A. He got better as the season wore on, however, and those improvements continue to yield results despite a two-level jump to Double-A. On Saturday, Kickham allowed three hits over six shutout innings and still has a zero ERA in his first two starts while striking out 11 over 9.2 innings and limiting Easting League batters to a .138 batting average. He has neither great stuff nor great command of it, but he generates a lot of ground balls with a low-90s sinker, although his slider and changeup are both no more than average. He entered the year as a bit of a sleeper, and he's showing back of the rotation potential.

Will Middlebrooks, 3B, Red Sox (Triple-A Pawtucket)
While Bobby Valentine was busy criticizing the effort of Kevin Youkilis, Middlebrooks was adding more evidence that he's the Red Sox third baseman of the future, delivering a trio of two-hit games and a pair of home runs to lift his season batting line to .364/.378/.636 in his first 11 games for the PawSox. There's no move coming anytime soon, especially with Youkilis starting to get going himself, but since Youkilis has missed an average of 43 games over the past three years, Middlebrooks will likely get a sizable opportunity to prove that next spring could be very interesting.

Jared Mitchell, OF, White Sox (Double-A Birmingham)
Mitchell's career hasn't exactly gone as planned since being a first-round pick in 2009, as he missed all of 2010 when he tore a tendon in an ankle and hit a miserable .222/.304/.377 for High-A Winston-Salem in 2011 with 183 strikeouts in 129 games. He spent a surprising amount of time with the big league club this spring, and even more surprising was how he didn't embarrass himself. That created some optimism heading into the year, and after going 6-for-9 with two doubles and a triple over the weekend, the 23-year-old is hitting .343/.511/.543 in his first 11 games for the Barons. He's still a plus-plus runner who can get down the line in under four seconds on a bunt, and while the strikeouts are obviously an issue, he has plenty of bat speed and when he does make contact, it tends to be hard. He's not on his way to any Top 101 list, but it would be foolish to write him off.

Domingo Tapia, RHP, Mets (Low-A Savannah)
There's been an incredible amount of great pitching at Low-A level names that prospect hounds generally know, but Tapia is far from a well-known player. A 20-year-old Dominican who had a 3.79 ERA with just 5.4 strikeouts per nine innings in the Appy League last year, Tapia has had one of the best pure arms in the Mets system since he signed. On Saturday it showed up in the box score as he whiffed eight over seven shutout innings while allowing just three hits. Tapia has an incredible fastball in terms of velocity, as the 6-foot-4, skinny right-hander was at 97-99 mph on Saturday, but he's dominating off the pitch, as while his changeup is ahead of his breaking ball at this point, both pitches are far from refined. He's an early-season popup guy who deserves notice so you'll know the name next time you see it in a box score.