How unlikely is South Carolina's Final Four run?

The Final Four is here and seeing Gonzaga, North Carolina, Oregon, and South Carolina as the remaining teams is something that only 657 out of nearly 19 million brackets predicted in ESPN’s Tournament Challenge. Looking through the lens of pre-tournament percentages as generated by ESPN’s Basketball Power Index (BPI), you really shouldn’t be that surprised that we ended up with these particular four teams heading to Phoenix to compete for the National Championship.

For starters, Gonzaga and North Carolina were the two most likely teams to reach the Final Four, at 45 and 48 percent likely to do so coming into the tournament, according to BPI. There were 14 teams with at least a 10 percent chance of making the Final Four, with Oregon sitting as the 11th most likely team to make it to Phoenix. While the Ducks were not the most likely team to make the Final Four, BPI expected an average of 3.3 of those 14 teams would make the Final Four in a typical year, and three made it this season.

The big shocker of the Final Four is obviously South Carolina. The Gamecocks were 28th in BPI going into the NCAA tournament, and 38th most likely to make the Final Four since they were in a region with Villanova, Duke, Florida, and Virginia – all top-10 BPI teams. BPI gave the Gamecocks just a 0.3 percent chance to make the Final Four, which is the second most unlikely team (after VCU in 2011) to make the Final Four since 2008. While it is surprising to see the Gamecocks in particular make the Final Four, it should not be surprising to see a team who had a small chance making it. There were a total of 35 teams with at least a 0.1 percent chance and less than a 10 percent chance to make the Final Four, and BPI expected an average of 0.7 of those teams to make it, meaning it was more likely than not that one of these 35 teams would win four games and get to play in the final weekend of the NCAA tournament.

Looking ahead, although it is possible, don’t expect South Carolina to continue its streak. Of the five most unlikely teams to make the Final Four since 2008 –according to BPI – only Butler in 2011 made it to the championship game. BPI gives Gonzaga an 88 percent chance to win in its semifinal matchup against South Carolina. The other matchup is expected to be closer, with North Carolina slight favorites at 57 percent against Oregon.

Now down to four teams, the outlook of the tournament looks eerily similar as it was on Selection Sunday --Gonzaga and North Carolina are the two most likely teams to be named National Champions -- although there is now a much smaller chance someone else is cutting down the nets in University of Phoenix Stadium on April 3rd.