I saw the match at Centre Court. It was a windy night and I think Maria was having problems with that (and with the lights). During the first set, both players were really on their games, but then Likhovtseva(?) called the trainer (umpire said it was due to blisters), and when the match resumed, Maria just couldn't control her unforced errors.
BTW, does Maria still do the "slap-on-the-hip"/ fist pump routine before her opponent serves? Because during that same match with Elena, I could hear her slap her hip from the very top of the stadium! I thought it must have hurt.