The NCAA Tournament has been as crazy ever this season, with higher seeds falling one after another in one of the wilder first weekends in recent memory. However, while there is always an element of randomness involved in a one-and-done tournament, there is an underlying pattern as to who is advancing and who is going home. For the most part, higher seeds with elite big men are safe while the ones without are vulnerable.

That's what separates Kentucky from the rest of the field. They start two 7'0 who will go in the lottery - Karl Towns and Willie Cauley-Stein - another 6'10+ guy who could - Trey Lyles - and they bring a 6'11 and 6'9 guy off the bench - Daraki Johnson and Marcus Lee - who will likely end up being first-round picks when their careers in Lexington are over. Kentucky pounds the ball into the paint and forces the other team to double the post, which opens up the floor for shooters like Devin Booker and Tyler Ulis. Cincinnati tried everything in their power to ugly up the game in their second-round loss to Kentucky, but there was just nothing their undersized front-line could do against Calipari's collection of Goliaths.

And while Kentucky was virtually assured of a place in the Sweet 16, the rest of their bracket was wide open due to the lack of size on the rosters of the 2-4 seeds. With Cliff Alexander suspended for the season, this version of the Jayhawks was one of the smallest groups Bill Self ever had, with a 6'8 guy (Jamari Traylor) and a 6'7 guy (Perry Ellis) starting upfront. There was no Cole Aldrich or Thomas Robinson or Markieff Morris or Darrell Arthur to run offense through and control the paint so there was no reason for Wichita to think they couldn't pull the upset. Notre Dame, which starts a 6'5 wing at PF, had to survive two nail biters against Northeastern and Butler. Maryland, whose best big man is a 6'9 stretch 4, couldn't punish West Virginia for having no one taller than 6'9 in their rotation.

Having future NBA players at the 4 and 5 positions is what separates the best teams from the rest of the field. In the West Regional, Wisconsin was able to outlast a game Oregon team because they could run offense through Frank Kaminsky (7'0 240), Nigel Hays (6'7 250) and Sam Dekker (6'9 220). In their second round game, Arizona punished a small Ohio State team that relied on a 6'5 shooting guard and didn't have the size to prevent Kaleb Tarczewski (7’0 245), Dusan Ristic (7'0 245) and Brandon Ashley (6'9 230) from dominating around the rim. The Buckeyes only chance was to play a lot of zone and the Wildcats had the shooting and passing ability to go 10-16 from 3.

To be sure, having big men isn't enough to stay alive in March. Every once in awhile, a team like Baylor with multiple 6'8+ prospects upfront will lose to a low-major team like Georgia State. But look at all the things that had to go right for Ron Hunter - Baylor turned the ball over 21 times, they had a 12-point lead with 2:30 left and they lost on one of the greatest last-second shots in Tournament history. A loss like that is what opens up a bracket and allows a 6 seed (Xavier) to romp into the Sweet 16.

Size was certainly the story in the South bracket, where the four biggest teams in the regional all made it to Houston. What was the difference for Duke this season than last? They had a 6'11 270 monster (Jahlil Okafor) they could run offense through, giving San Diego State virtually no shot of pulling the upset. In the Sweet 16, they will face a Utah team that starts a freshman 7'0 (Jakob Poetl) who will go in the first round whenever he declares for the draft. On the other side of the bracket, Gonzaga has a three-man frontcourt rotation of NBA prospects that goes 7'0, 6'10, 6'10 while UCLA tore through UAB behind a front-line with a 6'9 McDonald's All-American (Tony Parker) and a 6'9 future lottery pick (Kevon Looney).

Iowa State, the 3 seed in the region, is the perfect example of a higher-seeded team that was vulnerable because of its lack of size. They were absolutely destroyed on the glass by UAB in their first-round upset. While Jameel McKay (6'9 215) gave them the type of interior defender they had never had before under Fred Hoiberg, he didn't have the offensive game to impose his will on a smaller team, not in the same way as Parker or Looney. It's not that Iowa State was pre-ordained to lose early but that they had no margin for error against a lower-seeded team because they didn't have the type of elite size most higher seeded teams have.

That was the story in the North region, the only one where both the 1 seed (Villanova) and the 2 seed (Virginia) were knocked out before the Sweet 16. Villanova had Daniel Ochefu, but they didn't have the same type of depth and athleticism upfront as NC State, which rolled out four 6'8+ big men who could play. And while everyone focuses on the style of play that Tony Bennett has at UVA, the real reason why his teams don't tend to do well in the NCAA Tournament is they don't have the type of 6'8+ future NBA player who can dominate a guy like Michigan State's Matt Costello. If you can't make Tom Izzo pay for having an undersized front-line, he's probably going to beat you.

Everyone wants to focus on the guard play in the NCAA Tournament because they are the guys who have the ball in their hands for most of the game and who rack up the most conventional statistics. However, for as great as Shabazz Napier was in 2014, UConn would have lost in the first round without Amidah Brimah and DeAndre Daniels. Brimah was an elite 7'0 shot-blocker who will have a long career in the NBA while Daniels was a 6'8+ combo forward who could slide between all three frontcourt positions in the NCAA and was drafted in the second round. UConn spaced the floor and played defense like an NBA team - that was as much a factor for their Tourney run as Napier's heroics.

It was the same story for all the teams in that Final Four. Kentucky and Wisconsin had two of the deepest front-lines in the country last season and they combined for an epic Final Four game in Dallas. Even Florida, the smallest team in the bunch, started a 6'9 260 second-round pick (Patric Young) and another 6'8+ four-year senior in Will Yeguete. If you don't have the size to defend the paint, clear the defensive glass and get easy baskets around the rim, you are going to have an uphill battle in March.

If you want to figure out how the rest of the Tourney is going to go, all you have to do is follow the big men. Pretty much none of the teams in Kentucky's regional have the size to deal with them. Wisconsin is going to get a huge challenge from a UNC team with a bunch of 6'8+ McDonald's All-Americans in their frontcourt while Arizona should have a relatively easy challenge against a Xavier team built around an unathletic 6'10 plodder in Matt Stainbrook. How Jahlil Okafor fares against Jakob Poetl and either Przemek Karnowski or Tony Parker will go a long way towards determining whether Duke can make it to the Final Four.

The lack of elite big men in the North meant that was easily the most "open" regional in the field. At this point, there's no reason that Louisville or OU shouldn't think they can't make the Final Four, since Montrezl Harrell (6'8 240) and TaShawn Thomas (6'8 240) are as good as any of the big men on NC State and Michigan State. When all other things are equal, it's hard to bet against Tom Izzo or Rick Pitino in March. However, whoever comes out of this region will find all things aren't equal in Indianapolis, when they would almost certainly face three of the biggest teams in the field.

It's not that guard play isn't important but that most of the top teams in the country have high-level guard play. What separates teams are the big guys upfront, especially the ones who will play in the NBA, as they are few and far between at the NCAA level. Don't let the media's propaganda about perimeter players fool you. Basketball games are won in the paint and the teams with the size to do that tend to do pretty well in March.