I like the idea of not including preseason games in the coaches overall record. That way, you get a real sense of how good (or bad) the coach is.

also the NFL doesnt keep track of preseason games in the win and loss record for a coach

here is 2 examples

1st = https://en.wikipedia.org/wiki/Bill_Belichick
2nd = https://www.pro-football-reference.com/coaches/BeliBi0.htm

edit even the NFL sponsored teams dont do it either

here = http://www.patriots.com/team/coaches/roster/bill-belichick

Preseason games don’t count on your player card as it is now. Once preseason is over those games don’t get totaled anywhere