this makes sense, but i remain unconvinced chemistry applies to qb/wr. basketball is a sport of, for lack of a better word, frequent free-styling; players are often off-playbook in a way that football players very rarely are, like in the no-look ally-oop play that you described. you have convinced me that chemistry applies in off-playbook situations, where familiarity may be important, but in football almost all plays are so scripted (w/ the possible exception of the occasional scramble, in which perhaps familiarity becomes a factor) that familiarity with the playbook should tell the qb/wr everything they need to know, and familiarity with each other brings no new information to the table.