If you really want your jammies russled, go to ESPN's stats and take a look at dwar for all Jays players (this should make people hate baseball reference's WAR even more, which I think is what they use).
Interestingly, after looking closer at some of the numbers, Boni might actually rate positive defensively overall if you take away the ~50 innings he's played in center field. Removing the first 2 weeks or so of the season when he was a gong show at 2nd probably puts him above average defensively there too on both B-R and Fangraphs. Now if we could only get that horrid bat going.
http://espn.go.com/mlb/team/stats/fielding/_/name/tor/cat/defWARBR/toronto-blue-jays
edited: Included the link to ESPN's dwar.