Is it good to focus children on one sports when they're young?

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I had a chat today with a friend about raising daughters.  He has an interesting perspective.  He pushed his daughter really hard in soccer when she was very young.  He worked with her every night after work.  He sent her to camps.  As a result, she excelled quickly.  Through age 11 she was typically the best player on her team.  But, he's noticed an interesting trend recently...other kids are rapidly catching up.  It seems that kids with raw talent who didn't have the benefit of parental support are coming into their own. 

Was he right to push her so hard at one sport (at the expense of others) at such a young age.  Essentially, he believes that with all the extra work, she may have been artificially superior to the other kids.  In other words, it was never her raw talent that pushed her ahead.  Maybe if he had let her explore more sports and not worked with her so much, she may have been able to naturally pick the sport she could be the best at.

So, is it better to keep a safe distance, expose our daughters to many sports, and let them discover their true talents for themselves?