Lexi's caddie definitely seemed to be about as bad as I have ever seen at a tournament of this level. She would ask him a question, and he would take forever to give her an answer. Sometimes, all Lexi wanted from him was a word of encouragement, and he still paused for a very long time before saying anything. That pause alone gives a golfer some doubt, particularly when under pressure.
He also kept putting bad thoughts into her head, like "watch out for that water over there", when the water was never going to be an issue for where her shot was going to go. The guy seemed like a total goofball. Lexi might have won if she had a competent caddie--he was that bad.