There's also the matter of the fixed, deranged expressions they constantly sport. As long as the situation remains status quo -- the mascot is on the field, the sporting event continues, no contact is made -- mascots are easy enough to ignore or watch during down periods when they think they are not being watched, when they get distracted and wander around looking goofy. But as soon as anything out-of-the-ordinary occurs, that's when they get truly bizarre.
Like here, when one of them falls off a roof -- which is sort of funny, but also makes you feel kind of bad for the guy. Where the schadenfreude truly occurs, though, is in how the other mascot reacts. His gestures indicate dismay, but his grin remains demented, causing hilarity to ensue. Possibly even funnier is that, lacking any better option, he returns almost immediately to firing up the crowd.
And maybe that is the best course of action. Grief would only be more hilarious.