Relax. Breathe. The Raider Rusher is not Oakland's new mascot. It will not prowl the sidelines. You can summon it by repeating its name three times into a darkened bathroom mirror, but it will not trouble your dreams by showing up on an NFL broadcast.
Darren Rovell caused some panic yesterday by tweeting out that the Raiders would be unveiling a new mascot, but quickly backtracked—it's only for an NFL-themed kids' show. Exhale. Rovell's just doing some free advertising for the league he covers. According to a former employee who asked around, the Raider Rusher's appearances will be confined to the stadium's kids' zones and the like.
NFL Rush Zone has been on the air since 2010 without you noticing. ("Wow! Norv Turner, coach of the San Diego Chargers!")
It features "Rusherz," creatures like the Raiders' monstrosity. Every team gets one. They're all terrifying. Where do they keep their organs? They have to defend the galaxy from, I dunno, concussion lawsuits or whatever. But they are not actual team mascots, and unless you have particularly undiscerning children, you won't see the Rusherz unless you seek them out.
As for why the Raiders decided to extract their Rusher from the land of animated horror and produce a real-world abomination, we can only assume Al Davis's dying wish was to continue to scare children long after he's gone.