How they got here: When Dayton upset Gonzaga in the first round of the Maui Invitational back in November, the Flyers looked dangerous. Then they lost at Illinois State and at home to USC in the nonconference, and started A-10 play 1-5, and only emerged from obscurity when it was time to talk bubble in late February. Needless to say, few people saw Dayton outlasting Ohio State and Syracuse in the same weekend in Buffalo, N.Y., but that's exactly what Archie Miller's team did last week, thanks both to bad shooting by its opponents and opportunistic offense from a dynamic group of wings.
Key trait: Dayton's defense in its upset specials owed as much to the Buckeyes' and Orange's shooting woes as anything else. Syracuse famously made one shot -- one! -- outside the paint against Dayton. But the Flyers deserve credit for intelligent plans in both games, and for executing, especially by cleaning up on the defensive glass: Dayton grabbed 89 percent of OSU's misses and 69 percent of Syracuse's. It was enough.
How they got here: As Dayton showed, you usually don't go from bubble team to the Sweet 16 without getting a couple of breaks. Stanford's may well have been its draw. The Cardinal -- a marginal, decent, mostly overlooked team all season -- proved to be the wrong kind of opponent for both New Mexico and Kansas, which combined to shoot 9-of-37 from 3. Johnny Dawkins' team was especially expert against the Jayhawks: They zoned a poor-shooting team and begged it to let fly, closed off driving lanes for Andrew Wiggins, challenged every shot at the rim and rebounded KU's copious misses.
Key trait: Size. Among Stanford's starters are a 6-foot-11 center ( Stefan Nastic), a 6-10 power forward ( Dwight Powell) and a 6-7 combo forward ( Josh Huestis), and it brings 6-10 John Gage off the bench, forming one of the five or 10 tallest teams in the country. All four players rebound and protect the rim. Dayton is quicker and more skilled on the offensive end, but can the Flyers shoot it well enough over the top of the Cardinal's length?
Iowa State vs. Connecticut (Friday, 7:27 p.m. ET); Virginia vs. MSU (Friday, 9:57 p.m. ET)
How they got here: This veteran culmination of four years of up-and-down UVa basketball stumbled out of the gate, losing at Green Bay and by 35 at Tennessee (to say nothing of that 38-point outing in a home loss to Wisconsin in the ACC-Big Ten Challenge). But thanks to its lockdown defense and efficient, often overpowering scoring from Malcolm Brogdon, Joe Harris and Akil Mitchell, UVa has gone 21-2 and won the ACC regular-season and tourney title -- and their first two tourney games -- since that loss to the Vols on Dec. 30.
Key trait: At least three Sweet 16 teams play some form of pack-line defense, but only one coach can claim it as his birthright. In the late 1980s, Green Bay coach Dick Bennett -- Cavs coach Tony Bennett's father -- pioneered the gapping, matchup man-to-man defense employed by Arizona, Wisconsin and, naturally, Virginia. And boy, does it work: UVa ranks among the nation's 10 best teams in opponents' effective field goal percentage, offensive rebounding rate, 2-point shooting and points per possession. There is no such thing as an easy shot against this pack-line, and few second chances to boot.