I can't say I'm really upset by this news. As has been mentioned, Maria's game seems to have hit a wall in recent months and there's been no discernable improvement anywhere from her in 2013. But, ultimately, it's up to Maria to stay motivated and to want to continue improving. And I'm not one to throw out theories based on nothing, but over the past year or so, you've seen Maria start Sugarpova, start Twitter, start her Facebook channel, and devote more time to her boyfriend. Maybe Thomas didn't feel he was getting Maria 100% anymore out of her, lost some patience, and decided he had done all he could as a coach.
Maria's in limbo right now and I'm not sure which direction she goes. I could see her not winning much anymore, as she ages and finds more outside interests, and I could also see her making another determined push to be the best for the next couple of years and win another slam or two. But no matter who the coach is, SHE must make the commitment to be great and, it's just my opinion, I don't think Maria has given her all to tennis this year.
So, in the end, Thomas's legacy will be helping Maria embrace fitness and increasing her endurance, giving her the boost she needed to become a better clay court player, and leading her to that elusive French Open title. It was a great partnership while it lasted and they did benefit each other.