I agree with Bandit above, but, agree it doesn't take into account his terrible tackling and unwilling to SEEM to try to tackle. I would agree with this, but, tweak it and say Gilmore is a top 12-15 CB. But, that's a big hole to replace.
Also, he might have struggled with Rex's system or just didn't like playing for him.
I am a little all over the place on Gilmore, but, don't want to replace our #1 CB.