Its understandable, if anyone were to respect Mayweather's style or brand of boxing it would be Marquez. As Marquez is more into the technical part of boxing then most fighters, like Mayweather. Guys like Marquez and Mayweather when they look at fighters they don't look at speed and power, they look at them from a technical stand point.
It makes total sense Marquez would call Floyd #1 P4P. He got beat handily by Floyd (albeit the whole weight discrepancy thing taints the victory), and JMM has two very close fights against Pac. If he's going to lure Manny into another fight, it doesn't make much sense for Marquez to be praising him. Hec, if I was Marquez I would be proclaiming myself the better P4P fighter than Manny. It doesn't mean it's true, it's just smart strategy. Granted, probably nothing he says is going to work in making a third fight happen, but he should be trying considering the payday it will earn him.
The answer is in not being weight drained. It has already been established that Pac is on A-side Meth.