Good idea, but I see a fee problems:

- it is hard to define "successful play". "defined as 0 or more yards gained" doesn't cut it, as it will reward low-risk plays, and those sometimes are very bad. For example, with two seconds on the clock, 80 yards to go, and 5 points behind, gaining 1 or even 20 yards buys you nothing.

- I can still see adversaries game the system. Say I'm a fan of club C. Then, my strategy would be to gain reputation when this club plays anything but me, and then to use the hard-won reputation for a few crucial plays when this team plays my team. I won't get become the best fan, but if I have enough friends who do this, too, this will still make an impact.

- majority voting has two problems. Firstly, I think it will lead to dull plays; secondly, I think there will be a problem keeping fans who have minority opinions interested, and I fear that will be the majority of fans. You could prevent that by increasing a voter's weight whenever their choice isn't the winning one, and resetting it to the 'real' value when it is. That allows both the genius, the maverick, and the fool with minority opinions to occasionally have their choice picked.

You should go from 1 to -1; being consistently wrong is useful information, being randomly right or wrong is not.

you probably want this? https://en.wikipedia.org/wiki/Brier_score