12 years ago when Shanks was in his prime and had both his arms and could fight battles that shake the grand line.
Then he lost an arm and became a lowly yonko a title that is shared by likes of Buggy and Big mom.
Oda has literally spelled it out for us Shanks isn't worth mihawks time.
Just wait till we actually see mihawk in manga next time..you guys are in for a rude awakening