How to Get New Members to Stay?

[dirtbikerxz]

So give me advice on this guys. We always get over 20 new students (freshman) who signup on the "i have interest" sheet. But as soon as they find out that there is no way that there is a huge chance that they wont get to step on the field until they are atleast juniors, and even then they have to be better than others to get that position, 18 our of 20 people leave. This year we only retained one freshman. I try everything I can to keep them interested. I ask what they would like to do, I try to guide them and show them exactly how things need to be done, but they simply don't come back. Especially freshman, 90 perecent of freshman who join are super immature and kick the 2014 balls around and try to drill each others brains out no matter how much I and my mentors try to stop them, until eventualy we have to ask them to stop or leave. What do I do to get them to stop doing that.

Also out of the existing team (11 students) only 4 students actively take part during build season. SO that leads to us 4 having to do more than one task (like cading and programming and building for me). Since build season happens during baseball, soccer, and track season, the other 7 simply can't imagine skipping a day or two of practice a week to do robotics (even though I try to explain that I can find time from playing soccer, and two of the other three also do sports).
Anyone have any advice to rectify both of these problems? Thanks in advance guys.