It is not poor preparation. Marquez is a proud fighter. He also knows that a fight with PBF brings him recognition beyond hardcore boxing fans and money he never had before. He probably made more money in that one fight than his entire career combined. Remember the fight was contracted at 144.
We have to remember that their original fight date was even delayed by a few months when Floyd got that 'rib' injury. If it had occurred when originally planned, then JMM would've been in far worse shape.