If I'm Dan O'Dowd, I'm looking for an upgrade in CF, and at 2B.
I'd probably go with Carroll to see if his hitting spike was legit. His career OBP numbers suggest that they were, and he's a tremendous asset with the glove. Compare him and Matsui:
WARP3: (Wins over Average Player)
Carroll - 7.9
Matsui - 2.1 (if you multiply by three you get a 6.3, but I'm skeptical that Matsui is a .333 hitter)
EQA:
Carroll - .264
Matsui - .300 (with the .333 hitting spike)
FRAA:
Carroll - +26 (!)
Matsui - 0
Matsui's probably the better bet with the bat, but Carroll's glove make him a better player to pencil into your lineup. He also manages to get on base at a decent clip. Outside trade possiblities could be Ray Durham from San Francisco?
As for CF, Tavarez needs to be permanently relegated to a pinch-running role. Baker is intriguing, as long as he keeps hitting HR's. I don't know how he is with the glove. Reed Johnson is probably expendable in Toronto. He got on at a .390 clip, and hit 12 HR's. He's an average glove in center, with a plus arm. My hypothetical Rockies team would be:
1B: Helton
CF: Johnson
3B: Atkins
LF: Holliday
RF: Hawpe
SS: Tulowitski
2B: Carroll (or Durham slide to 6 hole)
C: Ianetta
Pitcher