Jennings, the Rays' No. 1 prospect, is ranked as the No. 7 overall prospect in MLB.com's Top 50.
"We wanted to get Desmond up here and we wanted to get Brignac better offensively," Rays manager Joe Maddon said. "There's no question Reid is a Major League caliber shortstop without question. And I don't like the idea of him not playing defense for us. But moving down the road we have to get better on the offensive side of the ball."
Brignac was the team's Opening Day shortstop and their faith in him bolstered their conviction to trade shortstop Jason Bartlett to San Diego. Brignac has struggled offensively all season hitting .193 with one home run and 10 RBIs.
"We just explained to him all of the different areas where we think he needs to get better," Maddon said. "We have to get very specific with the Durham people to make sure it gets followed through with. But that's it in a nutshell. Defensively, he plays here any day of the week for any team in the big leagues. Offensively, moving down the road we want to make sure all of this stuff is in order, because if you don't take care of it now, eventually it can drag out and then all of a sudden you don't like him as much as a shortstop."
Maddon said they felt Jennings was ready and that he's coming up to play every day in left field.
Jennings was lifted from the lineup prior to Durham's 4-3 win over Toledo on Friday night. He was hitting .275 with 12 home runs, 39 RBIs and 17 stolen bases.
"This [move] also permits us to rest other guys," Maddon said. "Get B.J. [Upton] off his feet, rest Joyce against a left-hander. There's different things we can do. Although you're going to see a lot less of [Justin] Ruggiano and [Sam] Fuld now that Jennings is with us."
Sean Rodriguez and Elliot Johnson will split time at shortstop.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.