Ngannou may very well be a victim of the UFC's own hype machine.
I frankly find it puzzling that the UFC hasn't gotten behind Stipe on this instead. He is about to set a record for HW title defenses, is likeable (not that NGannou isn't), a goddamn full time firefighter and an excellent representative of what MMA should look like.
Even Sherdog editors are picking Ngannou to win.
Stipe has vastly more experience and really only one career hiccup re Struve (And plenty of top fighters have had those one off performances, GSP for example). He lost a close fight to JDS and then came back and wiped him out and frankly Struve wouldn't make it out of the first round if they fought again.
Ngannou is largely unproven. He knocked out two aging heavyweights with collectively the most KO losses in the entire UFC roster. He hasn't fought more than 2 rounds his entire career so we have no clue what his cardio is like.
This is eerily similar to all the hype the Derrick Lewis had coming into his fight with Hunt. There he fought a guy that was tougher with better cardio and ended up paying for it.