When UCLA and USC traveled to Oregon last week, the smart money went as follows: The Trojans would give the Ducks a fight but wouldn’t withstand Oregon’s prolific offense, or the student insane asylum that is Mac Court. The Ducks then would give the Bruins all they could handle, before succumbing to UCLA’s withering defense and battled-tested talent.

Both games went down to the wire, each decided by two points. Despite a furious late rally to tie the game, Oregon lost to L.A.’s traditional second banana, USC. Two days later, the undefeated, no. 1-ranked Bruins staged a big comeback of their own to tie the game … only to watch the Ducks hit the winning shot with 13 seconds remaining as their ecstatic student section swarmed the court.

The proceedings in Eugene, Ore., opened the door for Arizona to grab a stranglehold on the conference. The once-beaten, no. 7-ranked Wildcats had won 12 in a row after an opening-night loss, fielded one of the best starting lineups in the country, and were traveling to Pullman, Wash., home of the Pac-10’s traditional hoops doormats, the Washington State Cougars. Final score? Washington State 77, Arizona 73.

The weekend’s results underscored something West Coasters have quickly come to realize: With apologies to the ACC, Big East, and other conferences, the Pac-10 is the nation’s toughest this season.

A look at the numbers drives that point home. Jerry Palm’s Web site, CollegeRPI.com, tracks RPI for all Division I teams and conferences. According to the site, the Rating Percentage Index “is a measure of strength of schedule and how a team does against that schedule. … It is used by the NCAA as one of their factors in deciding which teams to invite to the NCAA tournament and where to seed them.” The Pac-10 ranks no. 1 overall in RPI.

The difference between this year and recent seasons lies in the conference’s depth. Arizona has been a Pac-10 and national power for two decades. UCLA has returned to elite status under coach Ben Howland. And Lorenzo Romar has shaped Washington into a consistent threat. But beyond those three teams, the Pac-10 offered little in the way of secondtier power in the past few years: Once rock-solid Stanford fell behind other programs in recruiting; Oregon has struggled with erratic play since the Luke Ridnour-Luke Jackson era; USC fell off the map at the tail end of Henry Bibby’s coaching career, and Cal was a good — not great — standby that never went far in March.

The Pac-10 struggled to send more than four teams to the tournament in recent seasons (the ACC and Big East routinely send six, seven, or more — although the Big East at last count also had about 748 teams in its ranks). But more than that, it gained a reputation as being soft. This season, four Pac-10 teams — UCLA, USC, Oregon, and Washington State — rank among the top 40 defenses in America. UCLA’s defense led the Bruins to the national title game last season, and Howland’s obsession with hard-nosed, man-to-man D is well known.

But the Trojans’ rise as a defensive power is a new, downright shocking development. USC’s lack of discipline at the tail end of Bibby’s tenure — and at the start of new coach Tim Floyd’s — was constantly on display. The Trojans would fail often to account for three-point shooters, giving up scads of wide-open looks. When they’d finally adjust, teams would exploit USC with underneath passes for layups and dunks.

This season, the Trojans rank fourth among all D-I teams in Effective Field Goal Percentage allowed. A slew of athletic, longarmed, perimeter players have shut down opponents’ shooters and penetration, while freshman sensation Taj Gibson has emerged as a rebounding, shot-blocking force. USC’s increased patience and discipline have shown up on the offensive side too, as the Trojans have taken better care of the ball, cutting their turnovers. Where last season they attempted about 19 three-pointers a game, this year they’re looking for better shots, taking about 12 threes a game and making a higher percentage of both two- and three-point shots. With wins over top-20 clubs Washington and Oregon and a blowout of Oregon State, the Trojans are now one of four teams tied at 3–1 atop the Pac-10 standings.

USC’s only conference loss this season was to Washington State, the Pac-10’s biggest surprise. The Cougs have benefited from plenty of experience, with Wazzou’s top five players consisting of four juniors and a senior, and Derrick Low developing into one of the best lead guards no one ever mentions. Wazzou’s first-year coach, Tony Bennett, has followed in the footsteps of his father Dick. He preaches tight defense and slowpaced, patient offense in the highflying Pac-10. That tack would frustrate opponents but rarely led to victories in years past, as the Cougs would take games down to the wire before losing to the Pac-10’s elite. This year, they’ve become great finishers, holding on to beat USC by three in L.A. and taking Arizona to overtime before winning by four at home. Wazzou’s lone loss was a late blown lead, but UCLA has done that to many other teams in the past two seasons, too.

Fans of the wide-open Pac-10 offenses of years past needn’t fret — not as long as Oregon continues to run opponents ragged. Critics faulted Oregon for its weak nonconference schedule to start the season. But the Ducks’ dynamic, diminutive guards, Aaron Brooks and Tajuan Porter, have sparked an offense that runs at lightspeed. Oregon runs a four-guard offense; its lone big man, 6-foot-9-inch forward Maarty Leunen, is an excellent passer and deft outside shooter who’s more of a small forward than a center in many ways. Most impressive, the Ducks have succeeded without 6-foot-6-inch junior Malik Hairston, who may be their best player. Oregon showed both its biggest weakness and its greatest strength late in the UCLA game by letting the Bruins hit two, late threes over their small guards, then watching Aaron Brooks blow by UCLA’s entire defense to nail a corner jumper for the win.

When March rolls around, the Pac-10 could have six teams in the big dance. UCLA and Arizona are legit Final Four contenders, and the conference features four other top 25-caliber clubs in USC, Washington State, Oregon, and Washington (a highly talented team that features one of the country’s best freshmen in big man Spencer Hawes). Cal would be a seventh strong contender had center Devon Hardin not gone down for two to three months with a broken foot. At Arizona State, new coach Herb Sendek has landed some blue-chip recruits for the future, and Stanford’s basketball legacy means it’s never far from getting back in the hunt.

And what of bottom dweller Oregon State? As the Pac-10’s other nine will tell you, when you play in the best conference in America, you’re entitled to a break once in awhile.

Mr. Keri is a writer for ESPN.com’s Page 2 and a contributor toYESNetwork.com.