Do you have any evidence to support this claim, or are you simply trying to justify your personal dislike of a popular and experienced radio and television presenter?
In 2003, Claire Balding was the Royal Television Society's "Sports Presenter of the Year" and also won the "Racing Journalist of the Year". In 2012 she was awarded Sports Broadcaster of the Year. You're perfectly entitled to have your own opinions of her, of course, and she is frequently the target of irrational criticism because of her sexuality, but to say that she is "mediocre" is silly.
To say that she's 'mediocre' is giving an opinion. No one has to justify that, so don't throw stones in glass houses.
I don't like Terry Wogan. Are you now going to ask me to justify that? Please, get real!