From ESPN...
"Boston and San Antonio, in this case, can’t compete financially with Dallas, who have their full mid-level exception remaining (worth just under $4 million)...The Celts actually have the least to pitch financially of the three teams, sitting more than $5 million over the luxury-tax threshold and limited to offering a pro-rated share of the league minimum just as they gave Murphy."

http://espn.go.com/blog/truehoop/post/_/id/25631/latest-on-the-chase-for-corey-brewer

All I know is that JO and his full MLE better contribute something this year!!