You're kidding... Surprised you did not get threatened with leaving-the-club/lawsuit/tarring and feathering.
Unusual parent, that one...
I know, I was quite taken aback. This came in by email at 12.30 AM. It's ridiculously polite. The two kids are brothers and the football reference is about how one of them plays like American football and not soccer.
Coach Andy,
Thank you for saying something to my Mom about XXXX and XXX play and how they have been too aggressive. We wanted them on the same team this season but we knew there was the potential for their sibling rivalry to spill over onto the soccer field - thanks for your patience. In addition to my parents speaking with the boys after you said something while we were out of town I spoke with the boys tonight when I got home. I know what I was like at their age and I had to learn self-control on the field the hard way (by sitting out and / or getting penalized)...I'm glad XXX and XXX have a coach who cares about soccer being played the right way and wants to see boys grow into men. I fully support whatever you feel needs to be done to help them self-regulate the way they play in the heat of the action. I've asked XXX to be conscious of setting a good example for XXX by not getting chippy with him in practice, and I told XX I expected him to play soccer as a soccer player on the field and not a football player. If there is anything we can do to help, please let me know.