"We just feel we need pitching," manager Joe Girardi said. "Our whole bullpen has been used a lot. We didn't feel we have a lot of distance down there today, and so we felt we needed someone."
Betances was 6-4 with a 2.97 ERA, 88 strikeouts and four saves over 72 2/3 innings with the RailRiders this season. Adams batted .194 with two home runs and 11 RBIs over two stints in the Majors this season.
Though he started six games to begin the season, the 25-year-old Betances was moved to the bullpen in May and has thrived in that role, posting a 1.63 ERA in relief. Pitching two or three days at a time rather than pitching every five days has allowed him get on the mound more and build consistency and confidence, he said.
"I'm more aggressive coming out of the bullpen," Betances. "You kind of attack the strike zone right away. When you start, you kind of gradually get aggressive as the game goes on. It's one of those things where you have to come in and give whatever you have that day."
Girardi said he could use Betances in either a long- or short-relief role, depending on when he needs him.
The Brooklyn, N.Y., native hasn't pitched in the Majors since making two appearances for the team in 2011, when he allowed two runs on one hit over 2 2/3 innings. He missed part of the '12 season after suffering a right shoulder injury.
"Last year was tough, so to be here now -- I'm honored to be here," Betances said. "I'm thrilled to just come out here. Whatever situation I need to be used in, I'm ready for that."
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. Josh Vitale is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.