Marrero is going to play right until Drew comes back. If he is eligible at catcher in your league great, but don't expect him to catch too many games. And he will have move than 7 stolen bases. I'd go with him over A.J.
Go with Marrero. Also, Marrero will probably find his way in as catcher in enough games to remain qualified there for the next few seasons. Even if he only finds sporadic playing time after Drew's return, he could still outproduce AJ.