Has UNC Lost More at Home in Recent Years?

Recently ESPN ran a graphic during an ACC college basketball game that showed Roy Williams's home win percentage (at Carolina) as 0.792. A friend and fellow member of the marching band texted me "I feel like we've seen an abnormally high number of the other 20 percent", i.e. having gone to just about every home game, we've seen more losses at home in our time at Carolina than Roy's home win percentage implies. Thinking back to Austin Rivers, blowing it against Belmont last year, and losing close to Notre Dame and Iowa this year, I came to the same conclusion.

Roy has been the head coach at UNC for the past 12 seasons, so (as a senior), I've witnessed 4 of these. In these 4 seasons, our home record has been 57-9, which is actually 0.864. I've seen more Carolina home victories than expected, based on Roy's home win percentage. In fact, the Austin Rivers buzzer beater was the only home loss we had my freshman year.

However, my friend is a sophomore, so we'll look at only the past 2 years. While this year we were 9-3 at home (0.750), over the past 2 seasons we're 24-6, a win % of 0.800. Over 30 games, we would expect to see 6.24 losses, per Roy's home win percentage. Thus, losing 6 of those 30 games is actually spot on with this expectation.

This is an example of how we, as humans, remember unexpected events more vividly than the "norm", and so we overestimate how often these events occur. That, and many players, coaches, and fans alike share the notion that they remember the tough losses more intensely than the wins.