Honestly I don't think that is downplay. Mihawk is only the strongest swordsman by title but it is a heavily implied fact that he never beat Shanks so even if Shanks is a swordsman there is simply no reason for him to be weaker than Mihawk if you are honest. Oda also treats Shanks like a much bigger deal and associates him with Luffy while Mihawk associates with Zoro. As a writer I would do all those things to make it obvious that Shanks is at worst equal.