An American League All-Star in 2012, Harrison has made only three starts this season after spending the first three months on the disabled list due to back surgery. He was limited to six total starts the previous two seasons, also due to back injuries. In 2012, Harrison's last full season, the 29-year-old went 18-11 with a 3.29 ERA in 32 starts. In his major league career, he is 50-35 with a 4.21 ERA in 135 games (103 starts).
Williams, 21, was hitting .299 with 21 doubles, 13 home runs, 45 RBI and 10 stolen bases in 97 games for double-A Frisco this year. The left-handed hitter currently leads the Texas League in total bases (181) and ranks second in hits (113) while carrying a .341 batting average with runners in scoring position. Williams, who was a second-round selection by the Rangers in the 2012 draft, played in the All-Star Futures Game earlier this month and was rated the Rangers' fourth-best prospect according to Baseball America.
A native of Colombia, Alfaro was hitting .253 with 15 doubles, five home runs and 21 RBI in 49 games with Frisco this season. Rated as the Rangers' third-best prospect coming into the season by Baseball America, Alfaro was originally signed as an amateur free agent in 2010. Last season, he batted .261 with 17 home runs and 87 RBI in 121 minor league games en route to being named the starting catcher for the World Team in the All-Star Futures Game. The 22-year-old is currently on the disabled list with a left ankle injury.
Thompson, 21, was 6-6 with a 4.72 ERA in 17 starts for Frisco this season. He was selected to the Texas League All-Star team and was chosen to participate in this year's Pan-Am Games for the U.S. team. Last year, he went a combined 10-5 with a 3.12 ERA in 25 games (24 starts) with 130 strikeouts in 129.2 innings pitched and was also chosen for the U.S. team in the All-Star Futures Game. Thompson, a two-time minor league All-Star, was a second-round pick by the Detroit Tigers in the 2012 draft.
In 20 combined starts between Frisco and triple-A Round Rock, Asher was 4-10 with a 4.43 ERA. He has pitched at least 6.0 innings in seven of his last nine starts and allowed two earned runs or less in six of those seven starts. A fourth-round selection by the Rangers in the 2012 draft, Asher is a two-time minor league All-Star, having been named to teams in both the Carolina League (2013) and the Texas League (2014).
Eickhoff was a combined 10-4 with a 4.11 ERA in 20 games (19 starts) between Round Rock and Frisco this season. He was selected by the Rangers in the 15th round of the 2011 draft.
Hamels leaves the Phillies after 10 seasons with the club. He went 114-90 with a 3.30 ERA in 295 games (294 starts). The 31-year-old was the National League Championship Series MVP and the World Series MVP, both in 2008, pitched a shutout in the 2010 NL Division Series and, most recently, pitched his first career no-hitter in what would be his final start with the club. Hamels ranks sixth in Phillies history in wins, ERA and innings pitched (1,930.0), fourth in starts, and third in strikeouts (1,844), behind only Hall of Famers Steve Carlton (3,031) and Robin Roberts (1,871). He was the Phillies' first-round selection in the 2002 draft.
Another product of the Phillies minor league system, Diekman, 28, is 2-1 with a 5.15 ERA this season and 49 strikeouts in 36.2 innings. A 30th-round selection by the Phillies in the 2007 draft, Diekman compiled 100 strikeouts last season in 71.0 relief innings.