The Indians acquired Bauer with Reds center fielder Drew Stubbs and right-handed pitchers Matt Albers and Bryan Shaw, both of whom had been with Arizona. In return, the D-backs landed Reds shortstop prospect Didi Gregorius, veteran left-hander Tony Sipp and first baseman Lars Anderson. The Reds ended up with Indians outfielder Shin-Soo Choo, utility infielder Jason Donald and cash.
"We feel we're getting a young pitcher with a ton of potential," Indians GM Chris Antonetti told MLB.com. "A guy who we feel has a chance to pitch at the top of the rotation once he develops and a guy who we had longstanding interest in."
Selected third overall in the 2011 Draft, Bauer is MLB.com's No. 5 overall prospect. The UCLA product, who turns 22 next month, combined to go 12-2 with a 2.42 ERA in 22 starts between Double-A Mobile and Triple-A Reno this year. Called up to Arizona in June, he went 1-2 with a 6.06 ERA in four Major League starts.
"My gut is this kid is going to have a very good career," Arizona GM Kevin Towers said. "My hope is that this is a win-win for both sides with Cleveland and us. He was a tough guy to part with. We've got depth so that allowed us to make this sort of deal. For him, it's always going to come down to fastball command for him. If the fastball command is there for him with the repertoire of pitches he has, there's no doubt he's going to be a successful big league pitcher."
Bauer clashed with the D-backs during this season following confrontations with catcher Miguel Montero over game-calling.
"This season, although it was not good for him at the big league level, it was at the Minor League level," D-backs president and CEO Derrick Hall told MLB.com in November. "At the big league level, it was probably the most important season because it was his biggest learning lesson in his life.
"What we have heard from him lately is very encouraging. He realizes he has made mistakes and he wants to embrace his teammates and hopes that they forgive him. Just really positive signs and we see a lot of maturity from everything he went through."
Earlier Tuesday, the D-backs finalized a two-year contract with veteran right-hander Brandon McCarthy.
Among the three players coming back to Arizona is the 22-year-old Gregorius. Signed as a non-drafted free agent in 2008, he had been the Reds' No. 5 prospect. In his fourth Minor League season, the native of Curacao hit .265 with seven homers and 54 RBIs between Double-A Pensacola and Triple-A Louisville.
"I said the only way I would talk about Trevor Bauer is if I could get Gregorius," Towers said. "When I saw him, he reminded me of a young Derek Jeter. I was fortunate enough to see Jeter when he was in high school in Michigan. He's got that type of range, he's got speed, more of a line-drive-type hitter, and I think he's got the type of approach at the plate and separation to where I think there's going to be power there as well."
Gregorius was a Southern League midseason All-Star and made his big league debut in September and batted .300 with two RBIs in eight games.
"At Spring Training, I learned a lot," Gregorius told MLB.com in September. "They taught me a lot about how they play and how I have to play the game. I talked to them a lot and saw how everything is."
The D-backs also landed Sipp, who went 1-2 with a 4.42 ERA in 63 relief appearances this year, and Anderson, who appeared in 30 games over three seasons with the Red Sox.
Stubbs, the eighth overall pick in the 2006 Draft, joins the Indians after three seasons as Cincinnati's everyday center fielder. He boasts a .241 career average with 59 homers, 178 RBIs and 110 stolen bases in 137 attempts.
The Reds will replace Stubbs with Choo, a .289 lifetime hitter who has 80 homers, 345 RBIs and 80 steals since 2008. Cleveland was unable to negotiate a long-term deal with the South Korea native, who was paid $4.9 million this year and would have become a free agent following the 2013 season.
The acquisition of Choo could relegate stolen base champion Billy Hamilton to another season in the Minor Leagues. The Reds had sent their top prospect to the Arizona Fall League to transition from shortstop to center field.
The trade was the second blockbuster in three days involving a Top Five prospect. Late Sunday night, Minor League Player of the Year Wil Myers was dealt from the Royals to the Rays.