The Sox insisted the move was not made to displace Buchholz.
"By no means are we giving up on Clay Buchholz, far from it,'' said Epstein. "We still think he's going to be a huge part of our future and may well be an important part of our present. That said, we think this move gives us the freedom to do the right thing in our rotation rather than forcing people into roles because of injuries.''
Byrd was in Cleveland before Tuesday's game against Baltimore when the trade was announced.
"Give me a few minutes before I talk," Byrd said as he packed up in the Indians clubhouse. "I'm not lucid right now. I'm saying funny things. Give me a half-hour and I'll talk."
Byrd was at Fenway Park for Game 7 of last year's AL championship series on the day the San Francisco Chronicle reported he had used human growth hormone from 2002-2005. He then said before the game that he had used HGH for a medical condition but that he never injected the banned drug without a doctor's prescription.
"I have nothing to hide," Byrd said about two hours before Game 7, in which Boston clinched the ALCS with its third straight win. "Everything has been done out in the open. I have a reputation. I do not want the fans of Cleveland or honest, caring people to think that I cheated.
"Because I didn't."
He said in spring training that he met with baseball officials on Dec. 17 in New York but gave no details. He also said the offseason was "stressful."
For his career, Byrd is 104-91 with a 4.37 ERA for Cleveland, the New York Mets, Atlanta, Philadelphia, Kansas City and the Angels. He was drafted in the fourth round in 1991 by the Indians after he helped Louisiana State to its first College World Series championship, then reached the majors in 1995 with the Mets.
Byrd went 15-11 for Philadelphia in 1999 and made the NL All-Star team. He was 2-9 in 2000 and had shoulder surgery that forced him to miss much of 2001.
Byrd's best year was 2002 with the Royals, when he went 17-11 with a 3.90 ERA after signing as a free agent.
The Associated Press contributed to this report