So just how unlikely is this Final Four?

There's a word you're going to hear a lot of in the next week or so. Unlikely.

VCU's run to the Final Four was "unlikely." Butler's second-straight national semifinal appearance was "unlikely." Ending up with a No. 3, a No. 4, a No. 8 and a No. 11 seed in the Final Four was "unlikely." Having those No. 3 and No. 4 seeds come from the two toughest regions in the tournament -- where Ohio State and Duke reigned as No. 1s and the likes of San Diego State, North Carolina, Syracuse, Texas and Arizona lurked below -- was "unlikely." Seeing only two people -- only two! -- out of the 5.9 million Tournament Challenge participants on ESPN.com accurately predict the Final Four was, ahem, "unlikely."

Thing is, "unlikely" doesn't do it justice.

Implausible? Inconceivable? Unbelievable? Unfathomable? Preposterous? Insane?

Frankly, the only thing more unlikely than this Final Four is that we'll correctly choose an adjective to describe it.

Instead, let's let the numbers do the talking for us.

"If you take my probabilities literally (nobody does that, do they?) this combo had a 1-in-300 million chance of happening," Ken Pomeroy, whose influential KenPom.com tracks team efficiency rankings throughout the season, wrote in an email.

Pomeroy noted that his system "overstates" those odds, because his tournament projections "don't account for the idea that if VCU won its first two or three games, it could be assumed they were underrated and would have a better chance to win successive games than my system would imply."

Even so, the ballpark figure boggles the mind. And it should. According to Pomeroy, who released his tournament odds projections on March 13, Butler had a 1 percent chance of reaching the Final Four. The Bulldogs' odds of winning the entire tournament were 1 in 2,506. In and of itself, Butler's second consecutive appearance in the Final Four is enough to make us gaze with awe at the NCAA tournament's sheer unpredictability.

And then, of course, there's Virginia Commonwealth.

This is where things go from "wow, that's crazy" to "good luck wrapping your heads around this one, humans." Before the tournament started, VCU's odds of winning a national title were -- get this -- 1 in 203,187. In other words, the gap in expectations between VCU and Butler was roughly equivalent to the gap in expectations between Butler and, say, Ohio State.

Pretty much every projection system and oddsmaker saw the Rams as the longest of long shots. The New York Times' Nate Silver ranked VCU's odds of winning the national title higher than most, because Silver's system, unlike Pomeroy's, accounted for increased expectations in successive games. Those "higher" expectations? A 17,611-to-1 shot.

According to Silver, VCU's 820-to-1 odds of making the Final Four are among the longest in the history of the NCAA tournament. And if the Rams win the title, "they would unambiguously put themselves past both Pennsylvania’s 1979 Final Four appearance, and Villanova’s 1985 championship, as the most statistically unlikely success story" ever at the Big Dance.

How did we get here? In VCU's case, it's worth reviewing.

The Rams' indescribable postseason began on Selection Sunday, when the Rams were controversially counted among the final four at-large teams in the field. The selection didn't receive as much attention as UAB's, but VCU was top-of-mind for fans of Colorado, Virginia Tech, Alabama and a handful of other bubble snubs as one of the least deserving teams in the field.

The Selection Sunday analysts and angry Colorado fans weren't just picking on VCU for no good reason. The Rams finished in fourth place in the Colonial Athletic Association. Shaka Smart's team spent most of February losing, first to Northeastern and then, in its final four league games, to Old Dominion, George Mason, Drexel and James Madison. Before the NCAA tournament, VCU was 59th in offense and 143rd in defense in Pomeroy's efficiency rankings.

Frankly, the Rams had a decent season. Not bad. Not great. And one that offered very little hint of what was to come.

What was to come was, frankly, downright shocking. The wins -- over high-majors ranging from Kansas to Florida State to Purdue to Georgetown -- are crazy enough. The nature of those wins is another matter entirely.

Thanks to an explosive, hot-as-can-be offense, the Rams have averaged 1.17 points per possession against defenses ranked No. 1 (Florida State), No. 8 (Kansas), No. 12 (Purdue), No. 26 (USC) and No. 55 (Georgetown) in the nation in adjusted defensive efficiency. In the meantime, the Rams -- again, the No. 143-ranked defense before the tournament began -- held those teams to an average of .94 points per possession. VCU's average margin in victory? Twelve points. The Rams didn't just get to the Final Four. They steamrolled their way there.

"Hopefully this will blow away the idea that a team needs to be ranked 'X' in something to get to the Final Four," Pomeroy wrote in the email to ESPN.com. "It's not like [the Rams] were hot at the end of the regular season, either. It's the type of transformation that couldn't have been predicted."

In other words, not only do we have a No. 11 seed facing a No. 8 seed in the Final Four. Not only are both of those teams from smaller conferences. Not only is one of those teams a product of the First Four, and thus the winner of five tournament games rather than four.

Not only is all that true, but one of those teams did so by flipping on some sort of magic light switch, by morphing from a just-OK team into a suddenly dominant one. If your head is spinning, that just means you're like anyone else who watches, analyzes, or pays even casual attention to college basketball. Amazement is the only rational response to VCU's run. It's been that crazy.

For that matter, so has Butler's.

"The amazing thing is that Butler is the second-worst Final Four team since I've been tracking," Pomeroy said.

What's funny is that if it wasn't for VCU and Butler, we'd be sitting here talking about the unlikely Final Four runs made by Connecticut and Kentucky. Sure, compared with the Rams and the Bulldogs, those teams look like high-seeded, blue-blooded favorites. But compared to most Final Fours, Kentucky's and UConn's runs are surprising. This is the first Final Four in history that hasn't featured at least one No. 1 or No. 2 seed, and only the third Final Four since 1979 to feature no No. 1 seeds.

Considering both teams emerged from the two toughest regions in the bracket, well, let's just say Butler and VCU don't get to be the only surprises here. Before the tournament, Kentucky's odds of winning the NCAA tournament were 30-to-1. Connecticut's were 101-to-1.

If you want, toss aside the odds for a second. Ignore the statistics. Instead, take a stroll down hoops memory lane. Go back to February.

In February, Kentucky lost to Ole Miss, Arkansas, Vanderbilt and Florida. In February, Connecticut lost to Syracuse, Louisville, St. John's and Marquette. In February, Butler lost to lowly Youngstown State, its third straight loss and one that made it 14-9 on the season and 6-5 in the Horizon League. In February, VCU lost to Northeastern, Old Dominion, George Mason, Drexel and James Madison.

The notion that even one of these teams would, just two months later, be playing in the Final Four? It was a long shot.

The idea that all four are now here, that UConn and Kentucky will be joined by VCU and Butler? That's not "unlikely." Frankly, I'm not sure we have a word for what that is.

Instead, let's just call it the NCAA tournament, the only competition in sports in which 300 million-to-1 should always be greeted with the immortal words of Lloyd Christmas:

So you're telling me there's a chance?