Dude 90-91 is low 90's.
And we all know he has mediocre stuff, but he has good command and because of some deception to his fastball he can get swing and misses. He also throws a cutter around 87-88 mph, so that is why his fastball at times seems to have less velocity.
Rodriguez can pitch and has good command and tht is why he has been successful and should continue to do as he has done. He obviously will allow a few homers, but given the fact that he can get strike outs and does not walk many the damage should be moderate when he does.