Merriman is coming off an injury that takes more than a year to recover from. He doesn't have his burst, but I wouldn't bet against that guy from recovering.
Post the failed test, he averaged a sack a game while playing predominantly at a SS LB position (which is unheard of for a guy not playing the open side).
If AJ Smith trades Merriman to the Pats, he's given up on the season.