NEW YORK -- It remains to be seen if the intentional ball that John Smoltz threw to Alex Rodriguez on Thursday night will wind up as the last pitch in the career of a potential Hall of Famer, or even if it was his final act in a Boston uniform.

But this much became definitive on Friday: The Red Sox designated the struggling Smoltz for assignment, meaning the club has 10 days to trade him, reassign him to a Minor League affiliate or release him.

Though designating someone for assignment is often a signal that a team is cutting ties with a player, Red Sox general manager Theo Epstein made it clear that he is open to keeping Smoltz in the organization.

But in the heat of a pennant race and with other members of the starting rotation also struggling, the Red Sox no longer had the luxury to keep giving Smoltz the ball every fifth day.

The 42-year-old Smoltz made eight starts after recovering from right shoulder surgery, going 2-5 with an 8.33 ERA. Smoltz -- at the suggestion of the Red Sox -- flew back to his home in Atlanta to think things over.

"It's never easy," said Epstein. "I think we just felt like we had to try something different. It's never easy to tell someone they're designated for assignment, especially a Hall of Fame pitcher like that. I think it was certainly time to try something different.

"John understood and we asked him just to go home for a few days and think about what he wants to do, think about if he can still help. The good thing about the designation is that it buys some time to come up with the appropriate assignment. I'm sure I'll have something for you guys next week."

One source close to Smoltz indicated that the right-hander has not ruled out going to Triple-A Pawtucket or another Minor League affiliate to set himself up for a chance to help the Red Sox out in some form or fashion down the stretch.

"We're certainly open-minded to it," said Epstein. "I think the key thing is, we just asked John, he just pitched last night, to go home, think about things, and we'll touch base early next week."

The Red Sox weren't ready to announce who will take Smoltz's turn in the rotation on Tuesday against the Tigers at Fenway. It could be Junichi Tazawa, the 23-year-old right-hander from Japan who made his debut in professional baseball this season and was recalled from Pawtucket for Friday's game against the Yankees.

"We'll see," said Epstein. "It depends on what happens over the next couple of days. We'll have a starter for you, or a probable starter for you, sometime soon."

Smoltz, the ultimate competitor, perhaps expected too much out of himself after coming back from shoulder surgery for the first time. Red Sox catcher Jason Varitek feels strongly that Smoltz can still be an effective pitcher, and the only thing holding him back was the process of regaining his health.

"I think it's just him adjusting to his new shoulder," said Varitek. "I just know that the man has put in a tremendous amount of work to even be where he was. That's commendable in itself. The Baltimore start, what he went through to even take the ball for six innings -- that should be recognized."

Whether or not he throws another pitch, Smoltz has built one of the most impressive resumes of his era. He has 212 wins, 154 saves and 3,044 strikeouts, making him the only pitcher in history to reach all three of those milestones. In the postseason, Smoltz took his game to an even higher level, going 15-4 with a 2.65 ERA.

Until this season, Smoltz spent his entire career with the Atlanta Braves. As a prospect for the Detroit Tigers -- his hometown team -- Smoltz was dealt to Atlanta for Doyle Alexander in 1987.

Knowing that Smoltz would miss at least the first two months of the season in his recover from surgery, the Red Sox still had enough confidence in the right-hander to sign him to a one-year, $5.5 million contract that also had several incentives.

"I think we appreciated what his pedigree and his past was and respect it a lot," said Red Sox manager Terry Francona. "And he didn't let us down as far as [the type of] person he is, or his work ethic. He gave everything he had. He just got to a point where we think we need to make a change to help our team do better. But that would never lessen the respect we have for him and what he's accomplished in his career."

Whether or not that career continues is ultimately up to Smoltz, who seemed more frustrated than defeated at his lack of results.

"As you would imagine, he's used to getting better results and determined to find a way to do so. Now he has a lot to process," said Epstein.