Brown really struggled this year and has chronic back problems. I'm not sold on him at all. He spends way too much time on the ground. Not good for a guy with a back injury.
Knox is average to me. Doesn't have great hands, and not overly big. Also doesn't run great routes.
His production has mostly been on depiction and scheme. I think there are a lot of guys that Allen and play calling would make look good in the TE spot.