5.0 is indeed a perfect score, meaning that everyone picked that wrestler for first place.
A 4.0 would mean that on average those that picked, picked that wrestler second. A 1.0 would mean that on average that wrestler was picked to finish fourth.
Like last year (and the Big Tens and Maryland state high school championships), we will be conducting a prognostication contest for the NCAAs. Just pick the top four finishers in each weight class at:
http://danfisher.brinkster.net/ncaa/
Good luck.