Maddon said the veteran Percival, who fought a back problem late in the season, looked better when pitching a simulated outing Thursday, but Jackson still gives the Rays more of what they need.
"It was still about providing a little more length, and still not being sure if Troy could come back in back-to-back days, that was a concern." Maddon said. "And Jack provides that for us. And furthermore, he frees up David Price a little bit. The utilization of David becomes a little bit more free because Jack would be there to get the prolonged innings. So we thought we wanted length and we wanted something that would allow us to use David as something other than long or extra innings."
Maddon elaborated by saying that Jackson's addition to the roster would allow them to use Price situationally, though they will still be tuned in to see how Price, who has been a starter throughout his career, handles the bullpen -- specifically, how quick he can get loose and how quick he can pitch after an outing.
Maddon is not as concerned about how quick Jackson can get loose.
"Edwin is a horse, he absolutely can throw," Maddon said. "There's no concern about him. [He] got his work in between series. He's definitely pitched a ton of innings this year and finished strong. He's a strong young man, great arm stroke. And I don't have a whole lot of concern about him being used up."
Jackson sounded excited to be activated for the ALCS.
"It's a chance to go out and be a part of the team. I was part of the team anyways, but go out there on the field and actually play and help win a game," Jackson said.
Jackson didn't sound concerned about how he will be used.
"Any role I'm put in, once my name is called, regardless, I'll be ready," Jackson said.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.