Jamarcus in college was not as bad as what everybody is saying. His last year he had over a 68% completion percentage, 9.1 avg yards per completion, over 3,000 yards, and a 28-8 TD to INT ratio.
Also add in the fact that in 2006 (year before draft year) he had the 4th highest number of completions, 1st in completion percentage, 2nd in yards, 1st in yards per attempt, 1st in adjusted passing yards per attempt, 2nd in touchdowns, and 1st in passing efficiency rating.
On top of everything, he played for the RAIDERS. I'd give the guy a shot. Let him try to make the team with some quality leaders around him. Would be intriguing.