Fifty years ago, two things happened in college basketball that shall never be duplicated: UCLA won its seventh straight NCAA championship, and Bill Walton made 21 out of 22 shots in the title game.

Nobody knew it at the time, but a dynasty ended that night in St. Louis after the Bruins blitzed Memphis, 87-66. More significantly, the entire concept of a men’s college basketball dynasty died. Nothing since has approached the utter hegemony the Bruins exerted over the sport.

Duke came closest, reaching five straight Final Fours from 1988-92 and winning it all in the last two of those trips. Florida also won consecutive national titles, in 2006 and ’07. And that’s it, in terms of stacking championships directly on top of each other.

In fact, in the entire half century since UCLA won its seventh straight, no other school has won a total of seven championships. North Carolina and Duke each have won five; Kentucky and Connecticut have won four (with the Huskies having a shot at a fifth this weekend); Indiana, Kansas, Louisville and Villanova have won three.

At the time, the overwhelming expectation was that UCLA would add an eighth straight title in the 1973-74 season. Walton had a final season of college eligibility, and the Bruins carried a 75-game winning streak into that year. They appeared to be untouchable.

But that record streak was snapped at 88 by Notre Dame in January. Then David Thompson and North Carolina State toppled UCLA in the Final Four in double overtime, and the Wolfpack won the title two days later over Marquette.

John Wooden tacked on one more championship the following year, then retired. The greatest run in college basketball history was over, and there has been no going back to the days of a single, monolithic power in college hoops.

“I can’t imagine it ever happening again,” says ESPN analyst Jay Bilas, the foremost voice in the sport.

Beyond the sheer excellence of the UCLA players and Wooden—which we will get to in a bit—there are five main reasons for the disappearance of dynasties:

1. Player mobility: By the 1990s, the idea of a dominant player like Walton or Kareem Abdul-Jabbar (then known as Lew Alcindor) staying in school for four years was an anachronism. A lot of top talent skipped college altogether until the NBA instituted its minimum age restriction, and that created the one-and-done phenomenon.

Draftable players have stayed in college for as brief an amount of time as possible for several decades now, which makes it harder to sustain success. Even in the Name, Image and Likeness Era, which has kept some fringe NBA prospects in the college game for longer periods, those players aren’t Walton-esque superstars.

Also: the departure rate for the pros tends to remain high at programs that do win a title. Having grabbed that brass ring, many of those freshly minted champions want to move on. There aren’t a whole lot of teams like the Florida 2006 nucleus that won it all and still came back nearly intact to repeat.

2. A more competitive sport: There are more schools nationally that take basketball seriously and are pumping money—much of it football revenue—into their programs. “The sport was less mature (during UCLA’s run),” Bilas explains.

Outside of Kansas, the Big Eight wasn’t much of a basketball conference during the 1960s and early ‘70s. Same with the Southeastern Conference and Kentucky. The Southwest Conference was a non-factor other than Houston,. And there was no Big East Conference during Wooden’s time.

In the 21st century alone, UConn has become a major power from the Big East. Meanwhile, Baylor, Oklahoma State, Oklahoma, Texas, Texas Tech, Florida, Auburn, LSU and South Carolina have all made Final Fours from the Big 12 and SEC.

3. A bigger tournament: UCLA’s dominance came against smaller tournament fields, ranging from 25 to 32 teams. Of the Bruins’ 10 national titles won under Wooden, nine of them were accomplished in four games and the last one took five. Starting in 1985, six victories were required to win it all.

As Bilas points out, “I don’t think UCLA would have had too many problems with a No. 16 seed and the winner of a 8-9 game.” That’s true, but the added numbers of games—especially a second-rounder against a pretty good opponent—enhances the chances for an early upset. Ask reigning champion Kansas, which was knocked out as a No. 1 seed in the round of 32 by Arkansas this year.

4. A more balanced bracketThe tourney used to be much more geographically based, which meant that UCLA was annually pummeling teams from the lesser conferences out West. From 1967-73, the Bruins’ paths to the Final Four went through Wyoming, Pacific, New Mexico State (twice), Santa Clara (twice), Long Beach State (three times), Utah State, BYU, Weber State, Arizona State and San Francisco.

For several decades, the NCAA selection committee has lessened the importance of keeping teams in their home regions and emphasized competitive balance. In addition to playing more games to reach the Final Four, modern teams are playing more hard games.

5. The three-point shotThe advent of the shot in 1986-87 has been an equalizer, spreading the floor, elevating the importance of shooters and decreasing the dominance of big men. Getting hot from the perimeter in a single-elimination tournament can lead to upsets.

All of that said: don’t believe for a minute that UCLA’s great teams were overly lucky or merely products of an easier tournament era. For one thing, there was the pressure on the Bruins to win their conference or be left out of the field—as happened in 1966, the one year that UCLA didn’t win it all between 1964-73.

And the sheer talent was staggering. If Abdul-Jabbar wasn’t the greatest college player of all-time, then Walton was. Those are the only two legitimate choices.

Alcindor averaged 26.4 points and 15.5 rebounds while winning three national titles. Walton averaged 20.3 points and 15.7 rebounds while winning two nattys and playing in three Final Fours. (Freshmen were ineligible when both played.)

Walton’s resume has the added boost of that 44-point masterpiece against Memphis, shooting a ridiculous 95.5 percent from the field. Both the points and the shooting percentage still stand as championship-game records. And although the 6’11” Walton enjoyed a height advantage against the Tigers, it wasn’t much of one. He was guarded for much of the game by 6’9” Larry Kenon, a future NBA All-Star in his own right.

“The numbers were absurd, but the plays he made were just as impressive,” says Bilas, who opines that Walton is the greatest outlet passer ever and was the first great passing big man.

There is a tendency among some revisionists to downplay Wooden’s excellence, writing off that period of dominance as the product of two towering recruiting coups. Bilas isn’t having any of that.

“Yeah, he won five titles with them,” he says. “He also won five without them. Wooden was equally successful without those two as he was with them.”

When UCLA’s run crested half a century ago, college basketball was unknowingly plunging into a new era. One without dynasties. It’s unlikely that a dynastic program will ever come back—certainly not to the extent we saw from those Bruins.