1. Oden style confirmed as strongest swordsmanship, so or Roger was not a swordsman or he was overall stronger than Oden, in both cases this helps a lot Shanks's case and now he can perfectly been put above Mihawk.
3. Inu Suulong haki being strong enough to hurt Kaido, when some Zoro stans (before Ashura) stated that Zoro was among the few being able to hurt Kaido with his haki (like with tatsumaki).