"We just tried to determine who we were going to utilize more often," Rays manager Joe Maddon said. "And we chose those guys because of that. That was the extent of the discussion for Willy versus some other people.
"We just determined that these other guys that we've chosen, we have a better chance of using them more often than him. No slight against Willy. ... He's going to continue to work out with us here, and he's available if anything were to happen."
Aybar will stick around, while outfielder Brad Hawpe and catcher Dioner Navarro -- who are not on the roster -- will not remain with the team.
According to Maddon, Jennings is on the roster because of his speed.
"And also defense in the outfield; it's primarily those two things -- defense and speed," Maddon said. "And if you look at how we've been built all year, defense is a high priority for us. And you know how we move things along as the game's in progress, whether it's to pinch-run and possibly stay in the game, we like all of that."
The right-handed hitting Baldelli was in Wednesday afternoon's lineup in the designated hitter slot, and Maddon said he could be in the lineup at DH again on Thursday.
"Rocco, we can play in the outfield some, but we can't play him a lot," Maddon said. "He's more than anything a DH or a pinch-hitter. We could probably play him out there in shorter spurts. We're comfortable with that."
Jeff Niemann, who was the odd man out from the starting rotation, will be on the roster and pitch out of the bullpen, giving the Rays some flexibility. He is stretched out enough to do long work, but he has shown he can do quality work in a short stint, which he did Sunday at Kansas City when he struck out the three hitters he faced in one inning.
"He came out spitting fire the other night, so that was kind of nice to see," Maddon said. "These other guys [in the bullpen] will be in similar roles, which you have seen to this point."
Lance Cormier, Jake McGee and Jeremy Hellickson were left off the roster.
"Primarily [Texas] is a right-handed hitting team," Maddon said. "So that had a lot to do with our decision."
Should the Rays advance to the American League Championship Series, Maddon said the roster would be subject to change.
Here is the Rays' 25-man roster:
Starting pitchers: David Price, James Shields, Matt Garza and Wade Davis.
Relievers: Rafael Soriano, Joaquin Benoit, Grant Balfour, Randy Choate, Dan Wheeler, Chad Qualls and Jeff Niemann.
Catchers: Kelly Shoppach and John Jaso.
Infielders: Evan Longoria, Jason Bartlett, Sean Rodriguez, Carlos Pena, Dan Johnson and Reid Brignac.
Outfielders: Carl Crawford, B.J. Upton, Matt Joyce, Ben Zobrist, Baldelli and Jennings.