Notes: The most likely of the three to be an impact player in the Majors, Segura signed with Los Angeles out of his native Dominican Republic in January 2007. Now 22, he has surpassed 100 games in a season just once (at Class A Cedar Rapids in 2010), but that hasn't tempered expectations. Ranked as MLB.com's No. 44 overall prospect, the switch-hitting middle infielder (his more natural spot might be second base) batted .294, reached base safely in 35 percent of his plate appearances and stole 33 bases at Arkansas. He was batting .368 over his final 10 games with the Texas League's Travelers when the Angels brought him up to the bigs; he struck out twice in his MLB debut on Tuesday. He was blocked by the Halos' current duo of Erick Aybar (shortstop) and Howie Kendrick (second base). The Brewers have Rickie Weeks at second and Scooter Gennett coming through the pipeline. Segura is slated to join Gennett at Double-A Huntsville. With more experience -- and health -- Segura could become a slick-fielding, base-stealing, .300-hitting All-Star -- and not before long.
Notes: Hellweg, a 16th-round pick in the 2008 Draft, is a potential middle-of-the-rotation hurler. He made the transition from the bullpen while at Class A Advanced Inland Empire in 2011 and hasn't looked back. In this, his first full season as a starter, the 6-foot-9 right-hander went 5-10 with a 3.38 ERA and an 88-to-60 strikeout-to-walk ratio over 119 2/3 innings in 21 outings. He had recorded eight straight starts of six or more frames before being pulled early on Wednesday. If his changeup becomes at least average and his overall command improves, the 23-year-old Hellweg has enough -- with a mid-90 mph heater and solid secondary stuff -- to help out by next season at the earliest.
Notes: Like Hellweg, Pena is a 23-year-old right-hander who will go from from the Travs to the Stars. In 19 Texas League starts, he won six of a dozen decisions to go with a 2.99 ERA and 111 strikeouts against 42 walks. Last month, he showed his potential by striking out seven and allowing one over six scoreless innings. He works with a heater that peaks in the mid-90 range and a strikeout-caliber slider. Without a deeper repertoire -- and more command of it -- however, some scouts see Pena destined for the bullpen.
Andrew Pentis is a contributor to MLB.com. Follow him on Twitter at AndrewMiLB.
This story was not subject to the approval of the National Association of Professional Baseball Leagues or its clubs.