The 22-year-old Bowden allowed one run and three runs Saturday against the Marlins and was 0-1 with a 7.59 ERA. He is rated by Baseball America as the top pitching prospect in the Red Sox organization.

"It was a little bit inconsistent for him in the fact that when he first pitched a couple of times, it was out of the bullpen, which is a little different for him," Red Sox manager Terry Francona said. "He needs to establish some rhythm and some power in his delivery, because it's not that fluid."

Tazawa, also 22, signed a $3.3 million, three-year contract with the Red Sox in December after pitching for four seasons in the in Japanese Industrial League. He allowed one earned run and five hits in nine innings over five spring-training appearances.

"Tazawa was lights out," Francona said. "He just handled everything. Nothing threw him off. He was comfortable on the mound. He's the quickest guy to the plate on our staff. ... He just needs experience."

Bard, Boston's second first-round pick in the 2006 amateur draft, pitched 1 1-3 hitless innings Sunday against Philadelphia.

"He had a terrific camp, and his future is certainly very bright," Francona said. "All he needs to do now is go get repetition, and we told him that. We asked him to work just as hard in the minor league camp as he worked here, because he really did a good job."