Not a big fan of power structure of one piece , Whitebeard was cut above the rest among the 4 emperors , you have to realise in oda's world Roger , Prime Garp and Whitebeard are op of the power scale structure .
I am not big fan of powerlevels especially One piece fights are always messed up and oda violates the power structure to his wish so anything oda says is canon but he misses out at times when draws character like Im , rocks who are like Madara level in power structure . Unfortunately he is no better than kishimoto when drawing the fights .
Oda has hired new editor so hopefully he has chances to amend his past .