Discussion Forum—A Way with Words, a fun radio show and podcast about language

Baseball season is just starting, and the coach told me he heard that my 11-year-old son "has some water to swim in." (He's seen him only once, at tryouts.) Neither the context nor his tone of voice gave me any clue about whether this is a good thing or a bad thing -- he could have been saying that he has SOME water to swim in, implying a rudimentary skills base, or he could have been saying my son has some distance to go, or he could have been giving him at least a partial compliment (someone without any water to swim in would undoubtedly perform poorly). The conversation moved on before I could ask him for clarification.

What could he have meant? I can't find anything about this expression online.