It's just a matter of how you look at the war and staying consistent in how you judge characters.
People bring up Mihawk's slash to Whitebeard getting blocked by Jozu but ignore Kizaru's beams towards Whitebeard getting blocked by Marco.
In addition, Kizaru gets attacked by Marco and gets sent flying (although he was undamaged), this doesn't happen with Mihawk.
People bring up Mihawk failing to do anything fatal when he cuts Luffy but ignore Kizaru on 2 occasions doing minimal damage to Luffy (his 2 kicks and the beam which pierces Luffy). In fact, Dalmatian (the Vice Admiral) draws more blood than Kizaru. It's the same thing with Aokiji, he gets a hit on Luffy which draws some blood, but not anything crazy.
People bring up Mihawk getting blocked by Vista and ending the duel in an equal position but ignore that Aokiji v Jozu was pretty much the same thing until Jozu got distracted by Whitebeard's heart attack which let Aokiji get the free hit on Jozu. People also fail to bring up Aokiji and Ace clashing equally with named attacks of their own (understandably, because of their Devil Fruits).
People bring up Mihawk momentarily getting stopped by Crocodile (Crocodile doesn't actually get a hit on Mihawk) but ignore the fact Crocodile does the same to Akainu and actually manages to cut his logia form (not his actual body) and stalls him as well.
Just based on the Marineford showings of Mihawk and the 3 admirals, Mihawk's attack power looked second only to Akainu.
I would rank it like this (best to worst): Akainu, Mihawk, Aokiji, Kizaru.
Defensively, Mihawk wasn't hit by a single opponent throughout the entire war. Kizaru got hit once but didn't get damaged, he evaded everything else. Aokiji was hit by Jozu, but with little consequences. Akainu couldn't be touched by the likes of Marco and Vista.
I would rank it like this (best to worst): Mihawk, Akainu, Kizaru, Aokiji.
People fail to realise that the "bad portrayal" Mihawk received was also present for the Admirals. However, the admirals are for some reason free from criticism from most people.
I personally don't view it as bad portrayal.
Oda aimed to show us that the likes of Marco, Vista, Jozu, and Ace aren't push-overs against top tiers such as Mihawk, Kizaru, Akainu, and Aokiji. After all, they are the executives of the strongest pirate crew.
People also make the logical error of thinking that because Mihawk and Vista were equal for x amount of time, then an extended fight between the two would end as an equal match.