Like when Thor has been severely weakened by poisons and gases, and he even once got knocked out cold by a tranquilizer dart. (Journey into Mystery #118)
And lets not forget the infamous incident where he got knocked out by a "super bullet" intended for Black Panther. Granted, Thor was only out for a minute, but a KO is a KO.
While there were specific circumstances behind these instances, I still have a hard time comparing them to Thor getting hit by Sentry, then getting blasted by what looked like the force of a small nuke.
People on this board only want to talk about peak showings, but want to ignore all the low or average showings.
In my humble opinion, I would say what the punishment Thor endured in Siege #1 fit into his average, and maybe slightly above average when you consider that Osborn's intent was to kill Thor, but it appeared all that blast did was just KO him.
...I mean come on EVERY hero has had a low showing at some point...and this isn't even a truly lo showing like the Hulk to a snake or Iron Man to a lighning bolt or WonderMan to a pumpkin bomb....seriously
at least what hit Thor looked mighty impressive.