User blog comment:Luffayking12/haki vs. brute strength/@comment-3119203-20120129040251

Ok, to start off, just because Ace was Second Division Commander doesn't mean he is the second strongest (actually it would be third strongest, Whitebeard and Marco are higher-ranked than he is). The reason he took that position is just because it was an open slot. If the 14th Division Commander spot had been open, he would have taken that. The idea is that Whitebeard's Division Commanders are more or less equal, even though we can pretty clearly see it is not that way (if it was, the they had like 14 people on the crew at Admiral level). Oh, and none of the Division Commanders are ranked above each other, expect MAYBE Marco. All of them command their respective divisions, all of which are equal.

Ok, the haki thing. Haki is not an indication of strength either. Remember that a weapon is only as strong as the person wielding it, and haki is no different. A strong person with weak haki will easily defeat a weakling with a lot of haki. Sure, they can dodge attacks for a while, but as Luffy has shown, that won't last forever. Sure, most of the strong people in OP have haki, but they didn't get there riding off of just haki. The need other skills as well, namely brute strength.