My thoughts:
If you look at the blue section of the photo it is obvious that you are looking at a reflection off of an object. The way that the image is skewed show that the object is rounded with a hole in the middle, much like an inner tube.
example
ne I made
the next part of this is the number 5, since this is an anniversary year for first you start at year 1992 and add 5, 1997. In 1997 the game was called Torroid Terror and teams "human players score points by placing the inner tubes onto pegs on the goal, or around the top of the goal. The tubes are color-coded to identify team ownership."
You heard it here first folks, inner tubes it is. Personally I think Dave did this just so he could persuade Krispy Kremes to be a sponsor.