Semien, 24, should have the most impact and most immediate impact for the A's. He has exceeded expectations since signing as a sixth-round Draft pick out of California in 2011 and appears to be the frontrunner to start at shortstop for Oakland in 2015. He's an average defender at short, second base and third base, and he offers promising on-base skills and more pop than a typical middle infielder. In his first extended exposure to the big leagues, he batted .234/.300/.372 with six homers in 64 games this season, and he's a career .272/.374/.465 hitter in the Minors.
Phegley, 26, was a supplemental first-round pick out of Indiana in 2009 but profiles as a backup catcher. He has above-average arm strength and solid raw power, but he struggles with his receiving and his ability to hit offspeed pitches. He spent most of last season at Triple-A Charlotte, batting .274/.331/.530 with 23 homers and throwing out 44 percent of basestealers. He has hit .207/.221/.332 with seven homers in 76 Major League games during the last two years.
Bassitt, 25, was a nice find in the 16th round of the 2011 Draft out of Akron, where he pitched just 71 innings in four seasons. He broke out in 2013 by leading the White Sox system with 138 strikeouts, but broke his pitching hand in an offseason incident and didn't return to the mound until July. He still made his big league debut in the final month of the 2014 season, going 1-1 with a 3.94 ERA and a 21/13 K/BB ratio in 29 2/3 innings in six games (five starts). Used out of the bullpen during the Arizona Fall League, he led all relievers in the prospect circuit with 15.2 strikeouts per nine innings. Bassitt has one plus pitch, a 91-95 mph fastball, but just so-so secondary stuff (curveball, slider, changeup) and control. While he has the ceiling of a back-of-the-rotation starter, he's more likely to wind up as a reliever.
Bassitt is the only player in the deal to land on one of the two teams' Top 20 Prospects lists, landing at No. 19 on the A's list.
Ravelo, 22, had emerged as one of the best pure hitters in the White Sox system since signing as a sixth-rounder out of Hialeah (Fla.) High in 2010. He batted .309/.386/.473 with 11 homers in Double-A this year, leading the Southern League with 37 doubles. He has a sound approach at the plate and makes consistent contact, though the consensus is that he has below-average home run power, which makes it difficult to project him as a regular at first base. A former third baseman with a strong arm, he's an adequate defender at his new position.
Ynoa, 23, gets a fresh start after a star-crossed career in the Athletics' system. Signed for a then-international record $4.25 million out of the Dominican Republic in 2008, he missed his first season with elbow tendinitis and his third recovering from Tommy John surgery. In six years as a pro, he has totaled 161 innings and has yet to advance past high Class A. He spent 2014 at that level, going 4-2 with a 5.52 ERA and 64 strikeouts in 45 2/3 relief innings. Ynoa usually pitches at 92-94 mph and can touch 97, and he has a mid-80s slider that's more notable for its velocity than its break.
Jim Callis is a reporter for MLB.com and writes a blog, Callis' Corner. Follow @jimcallisMLB on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.