What every says is true, that kids should be multi-sport athletes. However, and this is something I haven't seen brought up as a result of the multi-sort athlete.
We all say and preach it's all about the team. We win as a team and we lose as a team. There is no I in team (insert well there is a ME). So if we all agree to this, then what about the girl that misses softball practice for a sokker game? What about the coach putting in a play that practice, but the girl is missing valuable information? This could go for the girl who misses sokker for softball? Parents complain that their dd is not playing, but as a coach, their missing practice for their other sport and missing out on valuable information is a no-brainer. Now at the travel levels, this can be easier; but what about the rec programs we all agree that are beneficial.
I saw it was also brought up about pitchers. I agree that most need to spend more time on their craft. A few years ago, when I coached; I had a parent pull me aside after a rec game and asked why I didn't pitch her dd. My response was a simple "how many times did she go out and throw?". The parent said "she didn't have time because of sokker practice." My reply was a simple, "that's why I didn't pitch your daughter. I need to see improvement and if she's playing in another sport, she loses in another area"
When my oldest played, she wanted to be the multi-sport athlete. I told her no based on the above. I wasn't about to allow her to hurt one team missing out on valuable information so she can play in something else, and then the next week do that to the other team. I did allow her to choice music and she became a very good violinist while working on her ball skills.
Now, the above doesn't apply to all. Just something more to think about. I do agree in multi-sport athletes, but not at the cost of either team. Secondly, the bodies need breaks. So I wouldn't recommend more than two sports. But TMHO.