A small army of reporters camped outside Arizona’s locker room Saturday at Wells Fargo Arena, waiting for words of wisdom from the Pac-12 coach of the year, Sean Miller.

When the door creaked open, the first man to emerge was Tyler Trillo, a walk-on guard who last year was a sub for Roger Williams College, a Division XVIII team in Rhode Island.

OK, that’s an exaggeration, but as recently as Dec. 6, Miller summoned Trillo and played him for 13 minutes in a victory over UC Irvine. Trillo was the best available guard who didn’t start that night.

Parker Jackson-Cartwright had a bum ankle. Allonzo Trier was in street clothes. Gabe York was playing for the Erie BayHawks, an NBA D League team.

That’s one reason Miller and not UCLA’s Steve Alford is the league’s coach of the year. Sometimes Miller had to coach by the seat of his pants.

Here’s another: Alford’s six leading scorers played 5,430 minutes in the regular season. Miller’s six leading scorers played 4,024 minutes.

Who had to do the most coaching? Miller, no question.

He didn’t even have a true point guard unless Jackson-Cartwright was on the court. PJC played 589 minutes; UCLA point guard Lonzo Ball is so good at what he does — the stereotypical coach on the floor — he might’ve been on the coach-of-the-year ballot.

Ball played 1,084 minutes, more than double PJC’s time at the point.

I’d like to think Miller received more votes than Oregon’s Dana Altman, the league’s 2015 and 2016 coach of the year, for something as overlooked as deploying sophomore center Chance Comanche 19 minutes per game.

Altman had the coaching luxury of using 24-year-old NBA draft prospect Chris Boucher, a shot-blocking rim protector with shooting range to 20 feet, for just 23 minutes per game. As hard as it is to believe, Boucher doesn’t start for the Ducks.

He barely gets more time than the 19-year-old Comanche.

Miller’s roster management and game-day X-and-O skills were more critical to Arizona’s success than that of the coaches at Oregon and UCLA. That’s what separates Miller.

Coach-of-the-year balloting in any sport, at any level, is often flawed and inaccurate, but this time, the Pac-12 coaches nailed it.

That’s not always the case.

Lute Olson was the league’s coach of the year seven times — 1986, 1988, 1989, 1993, 1994, 1998 and 2003 — but he once told me his best coaching job might’ve been 1990.

That was the year Olson replaced first-round draft picks Sean Elliott and Anthony Cook, and point guard Kenny Lofton. Arizona broke in three new starters.

In the first week of December, Arizona was swept at Oregon and Oregon State, losing emphatically 84-61 at Gill Coliseum. First-year Beavers coach Jim Anderson would be voted coach of the year; he inherited senior All-American Gary Payton and three other starters.

But when Arizona and OSU met three months later in Tucson, the final game of the regular season, Arizona won 87-60 to tie the Beavers for the league title.

Somehow, Olson piloted Arizona to a No. 3 seed in the NCAA Tournament that year. Minus Payton, Anderson never had another winning season at OSU, or won an NCAA Tournament game.

There seems to be one unofficial rule in coach-of-the-year balloting: the underdog story rules. Since 1990, the winning coach has not been chosen 13 times.

Stanford’s Trent Johnson was selected over 35-game winning UCLA Final Four coach Ben Howland in 2008. Why? Johnson, who had been 47-40 at Stanford, finished three games behind UCLA in second place. It was a fresh story.

Then it got old; Johnson quit a few weeks after the regular season and went to LSU, where he got fired.

A year earlier, Washington State’s Tony Bennett was coach of the year, a feel-good story in which he replaced his father, Dick, as WSU’s head coach following lousy seasons of 11-17 and 12-16.

Under the coach’s son, inheriting his father’s young talent, the Cougars went 26-8. Another dominating Howland Final Four coaching performance was bypassed.

No coach-of-the-year selection made less sense (to me) than the 2001 choice of UCLA’s Steve Lavin. His veteran team of future NBA players Matt Barnes, Earl Watson, Jason Kapono and Dan Gadzuric finished third and went 23-9.

Stanford, 31-3, spent seven weeks ranked No. 1, the greatest season to that point in Cardinal history and the coaching highlight of Mike Montgomery’s career.

Arizona, which finished second, reached the Final Four in a year Olson took a leave of absence after the death of his wife, Bobbi. The UA completed the regular season with a victory at No. 1 Stanford.

Nevertheless, Lavin, who was fired two years later, was voted coach of the year.

This year, with three winning choices available, the league’s electorate got it right.

Contact sports columnist Greg Hansen at 520-573-4145 or ghansen@tucson.com.

On Twitter @ghansen711

Sports columnist for the Arizona Daily Star.