The Bryce Harper Watch is now in full effect. Although the 18-year-old scuffled slightly out of the gate, the once-in-a-generation phenom apparently just needed contact lenses, and has been virtually unstoppable ever since. Harper had an 18-game hitting streak snapped Sunday and has been out of this world overall for Low-A Hagerstown. Harper is batting .366/.447/.656 with nine home runs, 31 RBI and six stolen bases through 36 games for the Suns. A promotion seems imminent. Thus far, Harper has been as good as advertised.
As for the rest of the farm scene, let's look at who's hot and who's not in this week's Minor League Barometer.
1. Casey Kelly, P, SD - The jewel of the Adrian Gonzalez deal (along with Anthony Rizzo), Kelly has allowed two earned runs or fewer in each of his last four starts for Double-A San Antonio. The 21-year-old has fanned 18 batters over that span. He has been effective overall for the Missions to the tune of a 3.38 ERA and 33:14 K:BB ratio through 45.1 innings. Perhaps most impressively, Kelly has posted a 2.23 GO:AO ratio in 2011. With the ability to keep the ball down, as well as miss opposing bats, Kelly has the chance to be a frontline starter for the Padres as soon as 2012.
2. Fernando Martinez, OF, NYM - Martinez recently told reporters that he felt like an old man, even though he is still just 22 years of age. However, it does feel like we've been talking about Martinez forever. Unfortunately for the Mets, his promise has been left unfulfilled, and many fear he is the next Lastings Milledge. Nevertheless, Martinez got called up to the bigs last week and smacked a home run for the Metropolitans on Friday. With Angel Pagan still a few weeks away from re-joining the squad, Martinez should remain with the team during that time, even if in a quasi-part-time role. Jason Pridie has been a pleasant surprise, but was never considered a prospect on Martinez's level, talent-wise. This could be F-Mart's last shot at proving he belongs.
3. Dustin Ackley, 2B, SEA - There are murmurs that a promotion could be coming shortly for Ackley. Over his last 10 games, the 23-year-old is surging with a line of .405/.469/.667, along with two home runs, seven RBI and even a stolen base. His availability at a thin position makes him perhaps even more desirable than his stats would normally make him in fantasy. However, make no mistake about it; Ackley has great presence in the batter's box, along with decent pop and speed. The M's are hoping he will develop even more power as he matures, and his glove work at second has improved vastly in the last year or so. All in all, Ackley looks destined for the bigs sooner rather than later.
4. Mike Trout, OF, LAA - You know the name by now, but it doesn't mean Trout has been any less productive for the Angels. Over his last 10 contests, Trout is hitting .300/.408/.575 with two home runs, seven RBI and two stolen bases for Double-A Arkansas. Trout continues to show better-than-expected power despite not hitting his stride on the basepaths just yet in 2011. Nevertheless, at just 19 years of age, Trout has a unique combination of power, speed and plate discipline that should make him a star for years to come. A September call-up remains a possibility.
5. Nick Addition, P, STL - Addition didn't find much resistance at Double-A this season. The 23-year-old lefty posted a 2.85 ERA and 32:5 K:BB ratio through 41.0 innings at Springfield. Opposing batters hit just .212 against him. This stat line earned him a quick promotion to Triple-A. His newfound control is something to watch, as he had a 109:53 K:BB ratio in 2010, and a 92:58 K:BB ratio in 2009. However, if the command is legit, the 46th round pick of the Cardinals in 2006 could be a diamond in the rough for St. Louis.
6. Zack Wheeler, P, SF - As if the Giants needed more starting pitching, Wheeler has been dealing for High-A San Jose. The 20-year-old righty has posted a 3.66 ERA and 41:13 K:BB ratio through 32.0 innings. Wheeler has fanned at least seven batters in five of his six starts this season, while also posting a respectable 1.48 GO:AO ratio. If he can maintain command and continue to get ground balls, Wheeler could be lights out for San Fran.
1. Allen Webster, P, LAD
2. Kyle McPherson, P, STL
3. Gary Brown, OF, SF
4. Todd Frazier, 3B, CIN
5. Kyle Parker, OF, COL
1. Miguel De Los Santos, P, TEX - The 22-year-old lefty from the Dominican Republic has shown massive strikeout potential, but perhaps he doesn't even know where the ball is going sometimes. De Los Santos has a bloated 8.04 ERA through 28.0 innings with Double-A Frisco. Opponents are hitting .265 against him. Though he has fanned 38 batters to begin the year, he has also walked 17 hitters. On May 2, De Los Santos allowed nine runs on eight hits in just 2.1 innings. He's had trouble keeping the ball down, and has been shuffled back and forth between the bullpen and the rotation as well. The talent is evident, but De Los Santos has yet to harness it for the Rangers.
2. Chris Carter, OF, OAK - The A's continue to struggle with their upper-level hitting prospects recently, and Carter has been no exception. He is battling a thumb injury currently, which has forced him out of action with Triple-A Sacramento since April 20. Even when healthy though, Carter has yet to prove that he can hit for average at the big-league level, and has not taken well to the transition to the outfield. Rumors abound that he may be headed back to first base when healthy. Though Daric Barton has been fairly poor this season, Hideki Matsui is entrenched at DH this season, and Carter has a long way to go before displacing either of them. His power is impressive, but overall Carter's promise remains raw and untapped. He might not be a full-time contributor until 2012, and that hinges upon whether he can regain his confidence at all.
3. Melky Mesa, OF, NYY - Signed as a 16-year-old in 2003, Mesa is now 24 years of age and maturing in Double-A, showing decent power and speed over the past two seasons. He has actually been hot of late, and had a career year at High-A last season despite being a bit old for that level, hitting .260/.338/.475 with 19 home runs, 74 RBI and 31 steals. However, overall his stats are sub par with Double-A Trenton this year, batting just .208/.280/.377 with three home runs, 11 RBI and three steals through 35 games for the Thunder. Mesa has fanned 43 times over that span, and has been caught stealing in six of his nine attempts. Having never hit above .260 during his career, and eclipsing the 100-strikeout mark easily over the past two seasons, concerns exist as to whether Mesa has enough plate discipline to cut it at the higher levels. Likewise, where will he play for the Yanks? Though the roster overall is rather old, the outfield is fairly young with Brett Gardner, Curtis Granderson and Nick Swisher.
4. Ryan Lavarnway, C, BOS - The Red Sox could use a catcher, and Lavarnway is among their better prospects. The 2008 sixth-rounder out of Yale has some power, but has failed to hit for average thus far this season. The 23-year-old backstop is hitting just .228/.302/.390 through 32 games with Double-A Portland. He's got six home runs and 19 RBI, but has also fanned 26 times. Lavarnway has really struggled against righties, batting a putrid .198 with 19 strikeouts. His eye has always been pretty solid at the dish, but Lavarnway is going to need to prove he can hit for average at the higher levels.
5. Simon Castro, P, SD - There appear to be legitimate concerns about Castro, who is allegedly having trouble with his mechanics. His stats would certainly lead to this belief, as he has compiled a 10.17 ERA and 21:18 K:BB ratio through 25.2 innings for Triple-A Tucson. Though he has not had a great start the whole season, his past start was particularly atrocious. On May 5, the 23-year-old righty lasted just 0.2 innings, allowing four earned runs on three hits. Castro walked two as well, though he did also strike out two batters. Opposing batters are teeing off on Castro, mashing to the tune of a .333 average. He's surrendered five home runs as well, after giving up nine in 140.0 innings all of last season. There's no need to write him off completely, but Castro definitely has some work to do before getting the call to the majors.
6. Chris Withrow, P, LAD - Withrow has been eminently hittable this season for Double-A Chattanooga. The 22-year-old righty has a 6.12 ERA, with opposing batters hitting .272 against him. He has also battled walk issues, tallying 15 walks in 25.0 innings thus far in 2011. Though the strikeout stuff is still there, and he has been getting a good amount of ground balls this season, Withrow is clearly missing his spots at times, and needs to improve on his consistency.
Follow @JesseLSiegel on Twitter.