He's hit .255 since his recall, and the Mariners are 15-6 when he's started in center. Thompson indicated that the club wants to use the remaining seven weeks of the season to solidify his situation, with Franklin Gutierrez also joining the outfield battery if he can return healthy from his fourth rehab stint in Triple-A Tacoma.
"We have to see what we have out there with Ackley in center field," Thompson said. "We kind of know what we have with Saunders in center and the corners. There's a chance we'll have Guti coming back -- and where he's going to fit in. So we're just trying to get Ack in there."
Raul Ibanez and Michael Morse will continue manning the corners, with Saunders also fitting into that mix. Ackley is the biggest question mark, given his inexperience at the position.
Ackley doesn't have the strongest outfield arm, but has good speed and is gaining confidence in his routes and ability to get to balls in the gaps.
"It's kind of like when he transitioned to second base," Thompson said. "He did a fine job. He started there for a year and a half without much time being there. I think he's comfortable in the outfield. He's played there before. He's comfortable when he goes over to first base, whether it be late in the game or what have you.
"Ack just kind of has that happy-go-lucky kind of attitude, where he doesn't get too excited about a whole lot, and that kind of helps him, moving around like he's doing. I think he's doing a really good job in center field. He's learning on the job here at the big league level."
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.