Best Kept Secrets in Sports?

When the Ime affair came out, I was surprised at how long it took to figure out who the affair was with (though workplace male/female situations may typically stay confidential). And was always surprised at how many people knew / how long it lasted w/ Lance Armstrong doping. I subscribe to the theory that once 10+ people know a secret or even 5+, it will always come out eventually.

Are there any secrets that have withstood the test of time in sports lore, or took decades to come out?