Juwan Johnson can serve as the Big X. He did it towards the end of last year.
I've been a proponent of converting him back to WR to play that role, but he can do it as a TE as well.
We need big a few big targets, but CKM could be using TEs as those targets.
Means is big at 6'2" 225lbs and crazy athletic so he could be the guy as well.