baseballfam4,
I'd say no, it's NOT a "play" as the coach(s) are expressing interest in you son. Coaches like to get up closer with player's their interested in and camps help them get a better look along with an opportunity to make a good impression on your son, particularly if your son has other colleges interested. Just how much interest your son really has in this particular school determines if it's worth missing a game. Going to a camp is one way for the coaches to hit two birds with one stone. That is, the camp provide an opportunity for an unofficial visit where the coach doesn't have to burn an official visit . . .and the coach gets that closer look at a player of interest.
If you're son has a GOOD high school coach, he will understand (well, unless it's a championship game
) and your son should talk to the coach about the opportunity to meet the coaches of the college he'd like to go to. But choose wisely and don't worry about going to a number of camps. Many such camps have other college coaches and recruiters at a camp. So, it may be worth simply choosing a camp that is well represented by colleges your son has interest in. With that in mind, if your son has lots of interest from a number of schools, I found that the camps don't do much as the college recruiters will be watching intently and will know they are competing for your son. And if your son has interest from only a couple of schools, then keeping the coach (or recruity coach) of the school of interest up to date that they can follow your son's games and any progress in thinking about a commitment, which is what they'll be after as they show interest. Oh, and the more interest you really show in a school, the happier the coach will be who's interested in you son. If your son shows interest in a lot of schools, coaches may not show a lot of interest as they may see that as someone who's undecided and not so interested in their school.
Coaches have restrictions as to how and when they can make direct contact with your son. It's best not to use a "middleman". . .unless the "middleman" is your son's HS coach. A good HS coach will most likely already know or have some kind of relationship with many of the college coaches and recruiters and can do some calling and promoting of your son. It's always best for your son to do the calling as other's have suggested and keep in mind that your son isn't likely to get a call back from the coach do to certain rules. But the coach can talk to your son when the son calls. So your son should keep trying (or do something like leave a message as to a specific time when he'll will call the coach again so the coach will know). College coaches and their recruiters tend to be quite busy and can be hard get hold of.
Since your son is a Junior, it's time to start making some decision and prioritizing which schools he really has interest in. And if there's one in particular and it's this one that has shown interest, then the sooner your son focuses on that school the better.
Make sure your son's academics match the school. A student athlete's has a rigorous work load between school work and baseball and you don't want your son get to a school and find that he can't handle the schools particular program.
I hope this helps some and sorry for be so long winded. I went through all this with my son just a couple of years ago where he had interest from many D-1 colleges. Now he's playing at his "dream college" and he couldn't be happier.