Re: 50+ Win Seasons
Serena - 3 50+ win seasons:
2002: 56-5 (8 titles: Scottsdale, Miami, Roma, Roland Garros, Wimbledon, US Open, Leipzig, Princess Cup)
2009: 50-12 (3 titles: Australian Open, Wimbledon, YEC)
2012*: 51-4 (5 titles: Charleston, Madrid, Wimbledon, Stanford, Olympic Games)
*after US Open QF
Kinda low, but I guess it's not that surprising considering she only played 50+ matches a season 1 other time (2008).
Career Grand Slam in your 20s? Been there done that. Career golden slam your 30s?
There's only 1. Serena.