Thornburg and Wooten are on the 40-man roster (which is full) with Minor League options remaining. Perez is a non-roster invitee.
The departure of Henderson (sent to Minor League camp amid velocity concerns) and Knebel (optioned to Triple-A), "just shrunk the pool," Roenicke said.
Thornburg remains a strong candidate as he works back from last season's elbow injury. He's been stretched out this spring in case the Brewers need a starter, but could also wind up in the bullpen as a long man. He owned a 2.79 ERA through five Cactus League appearances, including Thursday's start against the Giants.
Of Perez, who has allowed two runs on four hits in 6 1/3 innings and has shown impressive velocity, Roenicke said, "We have a full 40, but he's throwing the ball real well. He's got good stuff and he's succeeded in the big leagues. You know it's there. He's very durable, can give you multi-innings."
Cotts has not pitched well in camp (nine hits, four walks and four earned runs in 3 2/3 innings) but has enough of a big league track record that his spot is safe, Roenicke said.
Adam McCalvy is a reporter for MLB.com. Read his blog, Brew Beat, and follow him on Twitter at @AdamMcCalvy. This story was not subject to the approval of Major League Baseball or its clubs.