I think the whole he kept two calamities thing is just exaggerated, but that's a discussion for another day. The prime reasons for Marco's fall IMO are King and the exhaustion from fodder healing. Of course, Marco would've lasted a lot longer and fared a lot better without outside interferences. But again, King kept up with hybrid Marco in base for the most part. Exhausted or not, Marco's hybrid ain't going from top commander level to Cracker level just like how Boundman's strength won't be decreased to Snakeman level just because Luffy's exhausted.
