The coach should NOT be texting a 15 year old girl. What the hell could be so important at night? Unless it's a group text to the team, the dad should get involved sooner than later.
And for those who posted that this will alienate the dad, you must not have kids. Alienation would be the BEST CASE scenario. Worst case would be something you can read about in any paper almost EVERY DAY - a coach or teacher acting inappropriately. And the alienation would not last long, as the girl will figure out her dad is just protecting her.
Act on this NOW, dad.....before it's too late.