Well there’s probably a few modern day heavies where the size issue would simply be too much for Floyd. I don’t think Jarrell Miller is one of them.
He beat Gerald Washington and...uh...wach. and...duhaupas. oh! And he beat a washed up adamek. and he uh...beat the record at the all you can eat buffet in Brooklyn maybe? But he lost a unanimous decision to drug testing going 0-3. So with his shallow record and history of PED abuse, it's a complete mystery how he'd do with strict drug testing against a world class fighter, even if that fighter is like 80 lbs lighter and didn't have the best chin. Miller isn't exactly battle hardened or tested to begin with so it's not even outside the realm of possibility Patterson beats his ass or stops him.
The result would be a no contest when Miller failed his postfight drug screen. That is providing he passed his prefight drug screen, which is less than 50/50.
Patterson lights him up with speed. Miller’s never seen anything like Patterson and I doubt he’d make it past eight rounds.