John McEnroe in 1984 won 13 of 15 tournaments with an still Open Era record percentage of 82-3. He won 65.32% of his games for the entire years. The Games Won percentage is staggeringly great. If you have a one percentage higher Games Won percentage that is a big deal over the course of a year. To put it in perspective in Federer's best year for GW percentage he was in the 61% range.
McEnroe won two of three majors entered and was in the final of the other. Arguably the best year of the Open Era with a few other players.