A big reason why EJM didn't improve in his 2nd year, is because they weren't running the hurry up, which allowed for simpler reads.
EJM needs lots of work, and I don't think Rex Ryan knows how to create the right environment for developing QB's. I don't believe any QB will reach their full potential under Ryan.
McCown, Sanchez, et al... it won't matter much, because they will be playing small ball, and only attempting throws that are within the capabilities of most NFL journeymen.