Too easy.
Luffy stated Mihawk was too strong to fight but didn't do the same whe he faced 3 admirals at the same time. The manga puts Mihawk's strength above the combined powers of 3 admirals.
Mihawk easily handling Vista while he wasn't focus on him for part of the fight. That showed the huge gap between their strength.
Mihawk easily cutting in half a mountain size iceberg, that required the combined power of a yonko and admiral to create, from a great distance away with a casual attack while playing around. Big Mom would need to use her Elbaph spear attack to come close to that power.
Vista being surprised Mihawk knew his name. Vista didn't think his power level was strong enough for Mihawk to know him.
Mihawk became a renowned swordsman during the time Roger was alive and his crew was active. Nobody has spoken of about Vista strength in the same manner.
Crocodile went to Mihawk when he needed power to create a yonko level crew.
Mihawk went after the Marines and became known as the marine hunter. A large organization made up of thousands including a fleet admiral, 3 admirals, multiple vice admirals and more failed to beat Mihawk.