ST. LOUIS — When the horn sounded and Missouri walked off the Scottrade Center floor, the countdown began for the NCAA tournament selection committee to untangle one of the biggest mysteries of March.

Are the Tigers, overachievers during the regular season, more or less dangerous with Michael Porter Jr. in the lineup? Are they — and there might be no precedent for this question — better or worse with last year’s No. 1 recruit on the floor?

“I think we’ll be fine,” Missouri Coach Cuonzo Martin told reporters Thursday, and perhaps himself, following his team’s 62-60, one-and-done loss to Georgia in the Southeastern Conference tournament.

A year ago next week, Missouri hired Martin a few hours after he abruptly resigned at California. One of his first acts was adding to his staff a little-known assistant coach named Michael Porter Sr., who happened to be from Columbia, Mo., whose two daughters happened to play for the Tigers’ women’s basketball team, who happened to also have a pair of talented sons — the elder of whom happened to be the nation’s top-ranked recruit.

Michael Porter Jr., a 6-foot-9, 220-pound small forward and basketball prodigy, was released from a commitment to the University of Washington — where his father had been on fired coach Lorenzo Romar’s staff — and signed with the Tigers a few weeks later, and younger brother Jontay Porter reclassified as a member of the 2017 high school graduating class so that he too could join Missouri.

Anyway, it was almost poetic, how quickly and perfectly it all went down, and almost overnight Missouri shape-shifted from a program that finished 8-24 in 2016-17 to a team that legitimately had a chance to reach its first Final Four a year later.

“I always wanted to be the kind of player who makes a difference,” Michael Porter Jr. told reporters last autumn, a few weeks before the beginning of his freshman season and a new era at Missouri. “I didn’t want to go to a Kansas or Kentucky where I could be just another great player. I want to leave a legacy.”

Then last November, in front of the first sellout crowd at Mizzou Arena in four years, Porter played less than two minutes before hurting his back. Martin would tell reporters later that the star freshman had complained of hip and back pain, and as Porter sat on the bench with an ice pack on his side, Missouri fans couldn’t help but feel the heartbreak of the past.

This was a program that, five years earlier, was a No. 2 seed in the NCAA tournament before Norfolk State, of all programs, upset the Tigers. The same program that, in 2002, reached the Elite Eight before a scandal led to the firing of coach Quin Snyder, the program’s last great star figure.

The school predicted Porter, who would undergo surgery on two spinal discs, would miss three to four months — and perhaps the entire season.

But then the Tigers survived, knocking off ranked Tennessee, Kentucky and Texas A&M teams, and it was Jontay Porter who established himself as one of Missouri’s best players. He averaged 9.8 points and 6.8 rebounds, and with the star freshman sidelined, it was seniors Kassius Robertson and Jordan Barnett who each averaged double-digit scoring.

Missouri was good without Michael Porter Jr., so it was only natural to wonder: Could it be great with him?

A few days ago, school officials began whispering that Porter could return for the postseason, and Tigers fans did some whispering of their own. Could Missouri win the SEC tournament? Were its Final Four hopes back on track? A few of the more optimistic fans even allowed themselves to think about a national title, and those are the ones who’ll blame themselves after Thursday’s loss for the sin of psychological greed.

They’ll wonder what happened in St. Louis, less than 130 miles from the Missouri campus, even if it was as simple as a freshman playing like one — even if he has, for more than a year, been a walking promise of something superhuman.

On Thursday, Porter dribbled hard and fast, occasionally losing control of the ball. He left several of his three-point shots short, including one that missed the rim entirely. His feel was off, unsurprising after four months away, and he went 5 for 17 from the field.

“Maybe a step slow,” Martin would say, evaluating a program-altering player who has now played 25 total minutes for that program. “Instead of a 40-inch vertical, it’s 37. It’s just all those things, and just really going through it. I think the great thing for him, he actually went through it.”

Porter, for his part, said he wanted only to help his team, though for the next nine days — and likely beyond — Missouri fans and basketball analysts will wonder if Porter’s return to the lineup was actually disruptive.

The Tigers had survived Porter’s injury and absence, come together because of it, and were a likely NCAA tournament team because of how they responded. Now they’re disjointed and unsure, and double-digit scorers Robertson and Barnett scored seven and three points, respectively, against Georgia.

“We played, to me, about as bad as we played offensively, besides [Jontay], as we have all year,” said Michael Porter Jr., who finished with 12 points Thursday to his brother’s team-high 20. “So we’ve got some things we’ve got to fix, but it’s small things.”

Maybe, but now what? The Tigers, whom The Washington Post, ESPN and CBS had predicted entering Thursday would be a No. 8 seed, are surely more talented now than they were without Porter. So should they be granted a higher seed with a preseason all-American in the lineup and now with one game, disappointing as it was, behind him? Should they drop, considering their performance in St. Louis, and if so how unlucky would some future No. 2 seed feel if a 10-seeded Missouri — featuring a McDonald’s all-American in the lineup with almost no game footage to scout — to potentially prepare for in the second round?

It’s all very complicated, and Missouri did the selection committee no favors Thursday. Porter, anyway, has time to rest and sharpen his game before the next time — potentially the final time, considering he could leave school to enter the NBA draft after Missouri’s season ends — he suits up for the Tigers. Martin has time to consider whether his most talented player helps or hurts his team.

And the committee has time to consider where Missouri belongs and how it’ll shape the rest of the tournament, and the nine-day countdown is already running.

Correction: An earlier version of this story incorrectly reported that Missouri beat Florida when it was ranked, rather than Texas A&M and Kentucky.

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