As January comes to a close, the top teams in the country have begun to separate themselves. If we can learn anything from the last 25 years of college basketball, it's that this season's eventual national champion is likely ranked in the top 10 of the current AP Top 25. In 21 of the last 25 years, the national champion has been ranked in the top 10 of the final AP poll in January.

For the teams not listed below, here's the silver lining. In three of the last five seasons, the national champion was ranked outside of the AP top 10 (North Carolina in 2017, UConn in 2014 and Louisville in 2013) at the end of January.

RELATED: Breaking down the AAC, ACC, Big 12, Big East, Big Ten, Pac-12, SEC races

Here's a breakdown of the current top 10, with a reason why each team could win the national championship, the team's biggest weakness or potential flaw, and what a championship would mean for each school.

No. 1 Villanova (20-1)

Why they can win: The Wildcats are 20-1. They have the nation's most efficient offense and they're led by a pair of players – point guard Jalen Brunson and wing Mikal Bridges – who were members of Villanova's 2016 national championship team.

Why they won't: Villanova's leading scorer in the 2016 title game was then-sophomore guard Phil Booth, who scored 20 points on 6-of-7 shooting off the bench. The program announced the unfortunate news last week that Booth will be sidelined indefinitely with a fractured bone in his hand. Booth was the team's fourth-leading scorer this season and a 43-percent shooter from behind the arc.

Villanova's relatively tight rotation will get even tighter. Only eight players averaged more than six minutes per game before Booth's injury and now the Wildcats will have to replace his 28 minutes per game while he's out indefinitely.

What a championship would mean: Villanova would cement itself as dominant as any program currently in college basketball. They would have put together a four-year run of 30-plus win seasons, two national championships despite significant roster turnover (a feat which only has one recent historical comparison – UConn's titles in 2011 and 2014) and Jay Wright would become just the 15th men's basketball coach to win multiple national titles.

No. 2 Virginia (20-1)

Why they can win: They say that defense wins championships, so why can't Virginia – the team with the best adjusted defensive efficiency in the country – cut down the nets in San Antonio? The Cavaliers are 20-1 with their only loss coming on the road nearly two months ago against a West Virginia team that peaked at No. 2 in the AP Top 25.

Why they won't: It's hard to poke many holes in Virginia's resume, roster or advanced analytics, especially after the Cavaliers' road win at Duke. If anything, the team's style of play could lead to its downfall. Virginia plays at the slowest tempo in the country, which could leave the Cavaliers vulnerable to an upset if you follow the line of thinking that fewer possessions allows for greater statistical variance in a team's outcomes (e.g. the larger the sample size/number of possesions, the more likely it is that the better team will win. It's the same reason why there are more upsets in the single-elimination NCAA tournament than, say, the best-of-seven format of the NBA playoffs).

The Cavaliers have earned a top-two seed in three of the last four NCAA tournaments but they have just one Elite Eight appearance to show for it.

What a championship would mean: Bringing a national title home to Charlottesville would confirm Virginia's place among the premier programs not just in the ACC but the country, and it would silence any doubters who might question whether such a defense-focused, slow-tempo team can win a national championship in today's era of basketball. It would give Virginia a national title, potentially three ACC regular season championships (if the Cavaliers hold on to their conference lead this season) and four AP top-10 finishes in the last five seasons.

No. 3 Purdue (21-2)

Why they can win: Purdue is one of two teams in the country that ranks in the top 10 in both offensive and defensive efficiency – the Boilermakers are No. 3 offensively and No. 7 defensively – as of Monday afternoon, along with Michigan State. They're the No. 1 3-point shooting team in the country, making 43.6 percent of their tries from outside, including a herculean 20-of-33 effort recently against Iowa, which helps space the floor around their platoon at center that features 7-2 Isaac Haas and 7-3 Matt Haarms.

Why they won't: Similar to Virginia, Purdue's advanced statistics and track record leave little to nitpick. In this age of increasingly small, positionless basketball that emphasizes pace and space, can Purdue – even with its prolific 3-point shooting – win a title with Haas and Haarms? Also, a common thread among recent national champions is the presence of not just one, but often multiple elite lead guards. Sophomore Carsen Edwards leads the team in scoring at 16.7 points per game, so are he and senior P.J. Thompson (8.6 ppg) capable of running the show for a national title-winning team?

What a championship would mean: Purdue would break the Big Ten's national title drought, which is at 18 years since Michigan State won the national championship in 2000. It would be the best season in the Boilermakers' history, which currently includes just two Final Four appearances in 1969 and 1980.

No. 4 Duke (19-3)

Why they can win: Duke's starting lineup might be the most talented starting five in the country. The Blue Devils have the second-most efficient offense and they rebound 40.6 percent of their missed shots – the most in the country. They have multiple difference-makers in both their backcourt and frontcourt, and three different players have scored at least 30 points in a game this season.

Why they won't: The Blue Devils' defense, or the lack thereof, could be a real concern come March. While their defense has improved, they still rank No. 58 in defensive efficiency. Using kenpom.com's data that goes back to the 2001-02 season, every national champion has finished the year ranked in the top 20 in defensive efficiency. Also, Duke has made just 68.7 percent of its free throw attempts this season, which could come back to bite the Blue Devils in a close game in the tournament.

What a championship would mean: This would be coach Mike Krzyzewski's sixth national championship and the program's third this decade. If there is any debate about what college basketball program is operating at the highest level of sustained success, another title would probably end that discussion. Duke would also be among the youngest teams ever to cut down the nets, with the majority of the players in the team's rotation being freshmen or sophomores.

No. 5 Michigan State (20-3)

Why they can win: Along with Purdue, Michigan State is one of two teams in the country that ranks in the top 10 nationally in both offensive and defensive efficiency. The Spartans were ranked No. 2 in the AP Top 25 preseason poll for a reason. The have an All-American candidate in sophomore Miles Bridges, a point guard in Cassius Winston who's first in 3-point percentage (53.7 percent on 95 attempts) and third nationally in assist rate (43.5 percent), and a wealth of versatile frontcourt players.

Why they won't: Michigan State recently had a three-game stretch earlier this month that included a 16-point loss at Ohio State, an overtime win over Rutgers at home and and 10-point home loss to Michigan. In those three games, the Spartans were 65-of-156 (.416) from the field and had 18 more turnovers than their opponents. Their bench contributed just 23 points in those three games. In the two losses, they shot 7-of-25 (.280) and 3-of-13 (.230) from 3-point range, respectively.

For as efficient as Michigan State has been this season on both ends of the floor, it struggles with turnovers – both committing them and forcing them on defense. If the Spartans cough up the ball too often and there's a significant drop-off from their starters to their bench, Michigan State could find itself at home in March sooner than its players would like.

What a championship would mean: Michigan State would become the first Big Ten school to win the national championship since...Michigan State. The Spartans last won the national title in 2000, when they were led by the "Flintstones" – Flint natives Mateen Cleaves, Morris Peterson and Charlie Bell – and fittingly, Michigan State star Miles Bridges is also from Flint. Bridges' decision to stay in East Lansing for his sophomore season would have most certainly paid off as he and three other sophomore starters wound up leading the Spartans to a championship.

No. 6 Xavier (19-3)

Why they can win: Xavier returned four starters and two other rotation players from its Elite Eight team last season. Now, the Musketeers have a top-10 offense that's led by a trio of seniors in Trevon Bluiett, J.P. Macura and Kerem Kanter. 

Why they won't: The Musketeers rank outside of the top 300 nationally in turnover percentage on defense and they've allowed nearly 91 points per game, on average, in their three losses. Like Duke, despite how efficient the Xavier's offense is, can the Musketeers clamp down on defense and get a crucial stop towards the end of a close game against good competition?

What a championship would mean: Xavier has long been a springboard for successful college basketball coaches. Sean Miller left for Arizona. Thad Matta went to Ohio State. Skip Prosser moved on to Wake Forest. Pete Gillen climbed the ranks to Providence and later Virginia. A championship would make Xavier, a familiar name in the Sweet 16, a destination job and prove that the Big East packs a punch bigger than just Villanova.

No. 7 Kansas (18-4)

Why they can win: The Jayhawks have a top-15 offense and top-35 defense in terms of efficiency. They're one of the most efficient shooting teams with a 58.3 percent effective field goal percentage that ranks ninth nationally. Kansas has a veteran backcourt, with three upperclassmen – Devonte' Graham, Sviatoslav Mykhailiuk and Lagerald Vick – who are shooting better than 40 percent from 3-point range.

Why they won't: Kansas has a tight rotation – only seven players average more than eight minutes per game – which could prove to be perilous if redshirt freshman center Udoka Azubuike gets in foul trouble. The addition of mid-year enrollee Silvio De Sousa, a 6-9 forward, could help the team's frontcourt depth, but he has averaged just 3.2 minutes per game in his first five with the team. The Jayhawks have already suffered two home losses by double digits so they may be more vulnerable to an early tournament exit than the typical Kansas team.

What a championship would mean: After several months of questions about whether or not this would be the year that Kansas' 13-year streak of winning at least a share of the Big 12 regular season championship ends, the Jayhawks would have proven that they're as strong as ever. It would also be another indication that small ball lineups are here to stay, given that Kansas only has three big men on scholarship who are eligible to play this season and the Jayhawks rely heavily on their guards and wings.

No. 8 Cincinnati (19-2)

Why they can win: Cincinnati has the second-most efficient defense and second-best offensive rebounding rate in the country, a 12-game winning streak, and the Bearcats are projected to win the rest of their remaining games in the regular season, according to kenpom.com.

Why they won't: The Bearcats have played two teams that are ranked in the top 25 of KenPom.com's rankings – Xavier and Florida – and they lost both games. Cincinnati has one of the best records in the country but can it beat teams that rank among the nation's best?

What a championship would mean: Cincinnati won back-to-back national championships in 1961 and 1962, but the Bearcats haven't made it to the second weekend of the NCAA tournament since 2012. A title would mark the official return of one of the most prominent college basketball programs from the 1960s and 1990s, and it would be a major notch in the metaphorical belt of the American Athletic Conference.

No. 9 Arizona (19-2)

Why they can win: The Wildcats are 15-1 since returning from their disastrous Battle 4 Atlantis, which saw them go 0-3 and finish in eighth place. Their top-15 offense has a bonafide 20-point scorer in junior guard Allonzo Trier and a double-double machine down low in 7-1 freshman forward Deandre Ayton (19.5 ppg and 10.7 rpg). If their disastrous week in late November was truly the exception, not the rule for who the Wildcats are this season, they've played just about as well as anyone since December.

Why they won't: Arizona is an even more dramatic example of the prolific offense/not-stifling-enough defense profile that Duke and Xavier also share. The Wildcats are less efficient on both ends of the floor, however, than the Blue Devils and Musketeers, ranking 13th in offensive efficiency and 98th defensively. Arizona might win the Pac-12 but it needs to make major strides on defense if it wants to contend for the national title.

What a championship would mean: Arizona coach Sean Miller might own the title of "Greatest coach who hasn't made the Final Four." He's made the Elite Eight four times and the Sweet 16 on three other occasions during his tenures at Xavier and Arizona. If the Wildcats win the title, it would cement his place among the great coaches in today's game, Arizona would be operating at as high of a level of just about any program in the country, and it would mark the first time a team on the West Coast has won the championship since Arizona in 1997.

No. 10 Texas Tech (17-4)

Why they can win: The Red Raiders have the third-most efficient defense in the country, one of the most efficient and high-usage players in the nation in senior guard Keenan Evans, and wins over Kansas, West Virginia and Nevada, which are all ranked in the top 20 on kenpom.com.

Why they won't: Texas Tech has lost three of its last six games by a combined 37 points, including an 18-point loss at Iowa State, which is tied for last place in the Big 12. The Red Raiders' offense ranks outside the top 50 in efficiency and they're just an average team from behind the arc (34.8 percent). Scoring may not come easily enough for Texas Tech to make a run to San Antonio.

What a championship would mean: A national championship would be a major breakthrough in the second season of Chris Beard's tenure in Lubbock that would be almost impossible to overstate for one of the most unlikely title winners entering a college basketball season. Nine of Texas Tech's 15 NCAA tournament appearances have ended with a loss in the first round, so a title would represent unparalleled success for the Red Raiders, while showing that the Big 12 is currently the best conference in college basketball.

Andy Wittry has written for SI.com, Sporting News, the Indianapolis Star, Louisville Courier-Journal and Pittsburgh Post-Gazette.

The views on this page do not necessarily reflect the views of the NCAA or its member institutions.