I like that Caleb was already talking about improving his footwork and accuracy in the post game. Don't know about any off season restrictions, it not college, I suspect there isn't anything to keep Ben, Caleb, the receivers getting together for sessions/walk troughs, etc.
Did some searching, apparently, there's phases to formal team led off season work outs and limitations on coaches involvement. However, there's no restrictions on player led work outs.