First, before unveiling the top defenses for this coming season, a startling omission: There is no clear-cut best D in the country this preseason, and regular suspects such as Kansas and/or Virginia could yet crash this party.

The Jayhawks, unusually, didn't finish in or even very near the top five on that side of the ball last season. (Heck, they were merely "top-four" on defense in Big 12 play.) Maybe that means KU is "due," or maybe a group that won its 13th consecutive conference title and reached the Elite Eight anyway really has found a new way to win. We'll see.

Meanwhile, the Cavaliers did finish in the top five for defense but now Tony Bennett must replace three key rotation players in London Perrantes (who graduated), and Darius Thompson and Marial Shayok (who elected to transfer to Western Kentucky and Iowa State, respectively). I don't expect the Hoos to fall too far on D, but a top-five finish for that unit could be a stretch.

Without those two hearty perennials, it was a stretch to come up with five great defenses.

1. Louisville Cardinals

The Cardinals have been making their headlines off the court of late, of course, and as a result, Rick Pitino will serve a five-game suspension when his team begins ACC play this season. That alone makes Louisville a risky choice for "best defense in the nation" honors or any superlatives. Duly noted.

Strictly on paper, however, there's a lot to like with this group of Cardinals. Last season, Pitino's guys held ACC opponents to just 1.01 points per trip, despite the fact that Louisville was merely pretty good but not great at both rebounding misses and forcing turnovers. One of those "pretty good" traits might stay merely so-so in 2017-18 (and it might be defensive rebounding), but it's doubtful that both will. Plus, with a front line anchored by Ray Spalding and a reportedly beefed-up Anas Mahmoud, the Cards are going to force a high number of misses. Replacing Donovan Mitchell will be no small challenge on offense, but Pitino should once again have an elite defense when he returns from his suspension.

2. West Virginia Mountaineers

Last season in Big 12 play, the Mountaineers had the best defense in the league, and Bob Huggins is bringing back Daxter Miles, Esa Ahmad and -- oh, by the way -- reigning national defensive player of the year Jevon Carter. With Carter and Miles leading the way, Press Virginia could again force conference opponents to give the ball away on nearly one in every four possessions.

In fact, the WVU defense in 2016-17 was likely even better than it looked. The Big 12 made a whopping 39 percent of its 3s against the Mountaineers. That number is likely to drop this season, and as it does, Huggins and the Mountaineers will reap the defensive rewards. The only question with this unit, as always, is fouls. West Virginia has recorded far and away the league's highest foul rate in Big 12 play in each of the past three seasons. Huggins likely views this as a cost of doing business, which, in a way, it is. But it also represents an exceptionally large number of opponent points just begging to be raided and reduced.

3. Wichita State Shockers

Who knows, Wichita State might fail to live up to this lofty ranking. Last season, the Missouri Valley shot just 32 percent on its 3s against Gregg Marshall's outstanding defense, and the Shockers' new conference, the American, is almost certainly going to do better than that number in 2017-18. Add to that the fact that, unlike their old MVC foes, WSU's new league opponents will actually try to (gasp!) get offensive rebounds, and the potential exists for modest defensive slippage.

Then again, we're talking about a team on which literally everyone is coming back (assuming Landry Shamet recovers from that offseason surgery). Prolonged exposure to Marshall has often been sufficient in the past for defensive improvement, and these post-Fred VanVleet and post-Ron Baker players have been around their coach for a while. Plus Shaquille Morris consistently proves that rim defense and rebounding need not be mutually exclusive activities.

4. Villanova Wildcats

It has been easy to lose sight of the Villanova defense during this four-season-and-counting run of incredible shooting from the Wildcats. Nevertheless, the numbers are what they are: Jay Wright's guys have been the best defense in the league in Big East play in each of the past three seasons -- and in 2016-17, it wasn't even close.

Villanova will now try to keep this streak going without Josh Hart, Kris Jenkins or Darryl Reynolds. That's a lot to replace, but Wright has a lot coming back -- and in. Jalen Brunson, Mikal Bridges, Donte DiVincenzo and Eric Paschall all return. In addition, Phil Booth should be back from the injured list after missing all but three games last season, and 6-foot-9 redshirt freshman Omari Spellman will, presumably, be eligible. Throw in true freshman Jermaine Samuels, and Wright might well have enough talent on hand to once again rank among the nation's best defenses.

5. Texas Longhorns

Texas finished last in the Big 12 in 2016-17, but you actually don't have to squint too hard to call it, on balance, a solid first 17 months on the job for Shaka Smart. For one thing, finishing in "last" with five new starters in what statistically was the nation's strongest conference might not be quite as bad as it sounds.

Now the Longhorns have three starters returning (Andrew Jones, Kerwin Roach and Eric Davis) from what was, even in last place, a very good defense. Add 6-foot-11 freshman Mo Bamba, and you have the makings of one special defensive unit. Bamba's likely on a one-and-done trajectory, and if he can stay on the floor and out of foul trouble during his stint in Austin, opponents might find 2-point makes few and far between.