He actually played very well in preseason, he notched 3 sacks in about 6 quarters of playing time. It's just that the Rams were stacked at DE and the guy he was competing with for the final roster spot graded out as the best DE in the preseason. I said before the season started that he's worth a look but the Panthers are also stacked at DE and don't have room for him either. Now with Hardy and Alexander gone I'd say he's more than worth a spot at least on the practice squad just to see what he can do.
Just thought I would point out that two of Sam's 3 sacks came in last minute garbage time playing against Martin Wallace, a guy the Panthers just signed off the street to the practice squad. It's kind of hilarious, actually.