Jeremy Hellickson is pitching great in the tough AL East. (Icon SMI)

With the baseball season a third of the way complete, Baseball Press reviews some of this year's top performances from some of the game's best rookies in the American League.

This season, fans have already seen a talented crop of prospects make their major league debut in the AL, with additional talented prospects on their way in the upcoming months.

Despite his last disastrous start against the Baltimore Orioles, starting pitcher Jeremy Hellickson has been a terrific pitcher in the tough American League East this year.  Even though his strikeouts (6.1) and walks (3.6) per nine innings being down from his typical numbers, 10.8% of all Hellickson's pitches result in swinging strikes.  This is encouraging for his strikeout totals moving forward, since he's well above the 8.4% league average.  However, his ERA is likely due for some regression based on his .231 batting average on balls in play (BABIP) and the fact that he doesn't have a high groundball percentage, but with an increase in strikeouts, the spike in ERA won't be that drastic.  

Michael Pineda - SP, Seattle Mariners (6-4, 2.72 ERA, 1.04 WHIP, 3.48 SO/BB)
Seattle starting pitcher Michael Pineda has teamed up with Felix Hernandez to form a dynamic pitching duo in the American League West.  Pineda dominates hitters with a fastball in the high-nineties complimented by a slider that tails away from right-handed batters and runs down-and-in on left-handed hitters.  His 8.7 strikeouts per nine innings rank fourth in the American League among all starting pitchers with a minimum of at least 60 innings pitched.  With both King Felix and Prince Pineda under the age of 26, the Mariners are growing a good core of young arms for a years to come.

After an early season injury to Brian Matusz left a hole in Baltimore's rotation, the organization decided to promote Zach Britton to the show.  The 23-year-old lefty is a ground ball specialist, posting a 64% ground ball rate at Triple-A Norfolk in 2010 and has been continuing that theme in Baltimore this year with a 54% ground ball rate.  He wasted no time helping out an already young rotation by pitching at least six innings in his first six starts. Baltimore is starting to monitor his workload, as the team announced he'll skip a start here and there to give a him a few extra days rest and limit his innings.  Although he has just 5.2 strikeouts per nine innings this year, as long as he's keeping the ball on the ground, he doesn't need to blow hitters away.

It didn't take long for the Angels to give reliever Jordan Walden ninth-inning duties.  After veteran reliever Fernando Rodney blew a save during the first week of the season, the team handed the closer's job to Walden.  The hard-throwing righthander has a fastball that has seen triple-digits and currently ranks fifth among AL relievers with 14 saves.  He scuffled a little bit during the beginning of May, blowing three-of-six save opportunities, but he's converted his last seven opportunities.  Although his control has been shaky at times, his ability to strike out opposing hitters in 25.6% of all plate appearances coupled with the fact that he hasn't allowed a home run this season, has helped him stay out of serious trouble.

Catcher J.P. Arencibia had a memorable major league debut in 2010, collecting four hits and two home runs against the Tampa Bay Rays, and becoming just the fifth player in Major League Baseball history to hit two home runs in his first big league game.  Despite starting his career with a bang, he would go on to collect just one more hit over his final ten games of the season.  In 2011, the right-handed power hitting catcher's .786 OPS ranks fourth among all AL catchers with a minimum of 100 plate appearances.  He's crushed left-handed pitching thus far, hitting .372/.438/.767 with a 1.205 OPS in 48 plate appearances, but has struggled with righthanders, hitting just .203/.255/.399 with a .654 OPS in 149 plate appearances.  Although he's struggled with righties early on, he managed to keep his walk percentage around the league average during the months of April and May.

After mashing minor league pitching at the Triple-A level for a month, Kansas City finally called up their prized prospect Eric Hosmer in the beginning of May.  The left-handed first baseman was hitting .439/.525/.582 in 26 games at Omaha and clearly needed a new challenge.  The 21-year old has great plate coverage and is able to hit to all fields.  Although he hit five home runs in his first month of big league play, his game is geared towards hitting for average rather than power, but that could change as he develops as a hitter.

Honorable Mention: Mark Trumbo (1B, LAA), Mike Moustakas (3B, KC), Kyle Drabek (SP, TOR), Aaron Crow (RP, KC), Tyson Ross (SP, OAK)