I'm pretty sure Akainu went all out against WB. It just doesn't look like it coz the fight was too short. The others,yeah didn't quite gone all out probably because it's a war and conserving energy is critical and Mihawk didn't really fought anybody who's worth it aside from Vista which was postponed.
Originally Posted by Airicks
I actually think that it was a great indicator of strength. I could easily tell how still far Luffy is from the top tiers like Akainu. Before Luffy and Zoro needed to team up and use one of their strongest attack just to make a hole on Aqua Laguna. On the other hand WB can easily Create one, Aokiji can easily freeze one and Mihawk can easily cut one in half. Now Luffy can do a similar feat in terms of destructive power (the near destruction of Noah) but has to go totally all out in order to do so while Mihawk didn't even use a named slash when he cut down the huge frozen wave. In my eyes, Luffy can give any of the top tier a good sparring session but would still lose handily. Even Akainu would have gotten out of the way from a gatlling elephant gun.
This also makes me believe that Luffy would have to team up with someone, maybe Law Kid and Zoro when fighting Big Mom (if it's her) then the rest would go down leaving only Luffy and Big Mom but with a damage taken to even the fight out. Luffy's next Yonkou fight would be a one on one. By that time he's ready.