As far as protagonists are concerned, Mugiwara is the weakest of his own crew. With every new gain, be it haki or devil fruit shenanigans, his overall appeal is dampened. Likewise, the greatest adversaries Mugiwara faced can be found in the first half of the grandline with the exception of Katakuri. No other opponent beyond the Red Wall has forced Mugiwara to reevaluate himself in such a believable manner and confront his own shortcomings.