I live in curry hill, so grand central isn't such a bad walk that I need to take the subway. Since the subway takes me about an hour and 20 once walking is factored in, and metro north takes about 38 mins to the stadium, including walking, why not take Metro North? If I time it right I just pay the extra $5 and shave about 50 mins off of my commute to the match.
My marginal rate of substitution for an hour of my day is well over the $5 additional cost of taking metro north. So why take the subway?