Hmm. I'd forgotten he was found with no pants, good call.
My first thought would be they removed his pants before disposal, like for example if he was wearing tight jeans and they thought taking them off would help fit him in the suitcase or whatever they used.
It would be helpful to know, morbid as it is, where exactly the stab wounds were inflicted for a couple reasons, one being any wounds to the legs would make it very easy to determine whether his pants were removed before vs after he was killed. I guess we don't really need to know that though, I'm sure cops are fully aware of that and many other things.
Also going back to jerseygirl's post (sorry I don't know how to double quote), is it known for a fact that Joey went out the window at some point? I thought that was just one possibility that was being considered.
In any case, in a vacuum that seems like by far the most likely scenario that could have resulted in a broken pelvis, but in relation to everything else I personally know (which admittedly is not very much haha) it seems very complicated for that to fit. Was the thinking that he went out the window while still alive and returned to the building? That I could see. For any scenario, it's hard to believe there wouldn't be any witnesses though unless the apartment overlooked an alley (as opposed to the street)--is that something that's known at this point?