I get that he didn't have his full gear. I am just suggesting he may have had his helmet based on the picture. Maybe I am seeing it wrong which is why I just threw it out there. Maybe it wouldn't even fit in that, but I am just saying have a look. They have confirmed he had his water bottle now. It is totally feasible for his roommates to see his bigger bag (pads/stick/cleats) and say he didn't have his gear. Why water bottle and helmet? If you look up lacrosse hazing, it is drinking and often involves wearing the helmet out in public as part of ritual.
Big speculation on my part. I know. Police have said no foul play. It would just be clearer if the lacrosse meeting was known to be a total fabrication or not.
Again, I find it hard to believe that this would not be known by now if this happened. To may people involved to keep it quiet, but could've been a complete accident. Go off campus, party too hard, get disoriented, end up in wrong place or just have accident in total random spot.