Fleebeard in flashback
Clashed equally with Oden who was one tapped by Roger.
Clashed equally with sick dying on his last knees Roger.
Ran away from marine ships
Simp'd hard for Shakky
Ran away from Garp with his moustache tucked behind his legs.
World's Strongest Man my ass.
WSM = World's Scurriest Man
There is a reason Roger gave his son to garp instead of the guy who literally had orphans in his crew.
Also Oda literally made two pirates like Roger and Rocks being the top, would have been very anticlimatic having Garp the strongest marine below 3 pirates, 2 is fine, but even whitebeard hell nah.
Whitebeard is like the in-between Rayleigh and Roger level, I think Shanks is on his level, since he lost an arm and probably sacrificed his potential to surpass Roger, he would probably lose like a prime Whitebeard. There is a reason shiki claiming it was wb Era only after Roger was dead.
Oda has this habit of making some vice captain / wing characters as someone that can be seen as comparable to some captains, Whitebeard is just basically the Rayleigh of rocks.