There's been a lot of discussion in the post-game thread on CPJ's decision to go for it rather than kick the field goal at the end of the first half. On the way into the locker room he admitted he made a bad call and should have kicked it, but he was being really aggressive. Here I am going to "show my work", kicking the field goal was the correct decision.
Rather than looking at a football score in terms of points, look at it in terms of how many possessions the lead equates to. A 7 or 8 point lead is a 1 possession lead, with one drive the opponent can tie the game. Whether an opponent will Go For Two needs to factor into your decision making, but since this is in the first half and it's far too early to attempt two point conversions we'll say a 7 point lead is a 1 possession lead. What is a 4 point lead? A 4 point lead is a .5 possession lead, you are in the lead but one drive from the opponent results in you trailing by 3 and now trailing by .5 possessions.
So, let's consider two different scores at the end of the first half. First, a hypothetical 20-10 lead. This is a 1.5 possession lead, with two scoring drives the opponent takes the lead in the game. If you kick a field goal in this situation the lead increases to 13 points, which is still a 1.5 possession game. Fourth and 2 is riskier than fourth and 1, but by all means go for it. When you go for the first down you aren't risking much of anything at all.
The actual score on Saturday was 21-10. Kicking the field goal increases the lead to 14 points, which changes the lead from a 1.5 possession lead to a 2 possession lead. Two scores from the opponent and then you possess the ball in a tied game instead of trailing. That is a meaningful difference. Kicking the field goal has an immediate effect that makes it more difficult for the opponent to win the game, so kick it.