You might be confident but you are wrong.
It is a very good time for a girl but lots of baseball players can run that.
I'm happy for you to show me some data that proves me wrong. (I made my assertion without data, just based on my experience, so fair play).
My experience is that almost no baseball players run a mile that fast because it's a waste of time to train to be able to. It's not a skill that really translates in baseball. The 40-50 miles per week training to run a low 5's mile is better spent in the cage, weight room or field. I don't doubt that "lots" of young male athletes could train to run that fast, only that many would bother to.
The softball player you referred to as a top 15 player, is, almost by definition, an outlier (top 15 after all). To categorize 5:15 as a "very good time for a girl" is just an absurd dismissal of its rareness among non-track athletes.
But, again, I don't think mile time is a very important measure of anything for either sport (baseball or softball).