Old soldiers never die, Gen. Douglas MacArthur said when he retired, they just fade away. Yes, but the Kansas University men’s basketball roster doesn’t contain a single old soldier.

In order for a circus to leave town, workers must fold the tents. True, but the Jayhawks don’t have any roustabouts.

So why in the world did Kansas, facing the No. 1-ranked team in nation in front of a shoe-horned, ThunderStix-wielding throng in KU’s den of din, fade like a cheap T-shirt and fold like a house of cards in the second half?

“I have no explanation for that whatsoever,” said KU coach Roy Williams, who suffered the ignominy of watching a Kansas team blow its biggest lead ever — 20 points — while bowing to Arizona, 91-74.

So bad was it that if Arizona had made another three-pointer — and it seemed like the Wildcats drilled every trey they shot in the second half — the ‘Cats could have claimed they were down by 20 and won by 20. As it was, being ahead by 20 and losing by 17 was disappointing enough for the Jayhawks, who are now officially in a midseason slump.

Or at least Kirk Hinrich and Aaron Miles are.

Hinrich, Miles and Keith Langford made a combined 9 of 39 shots in Wednesday’s stunning 60-59 loss at Colorado. Langford snapped out of it Saturday with a 27-point explosion, but Hinrich and Miles still are clanking and clanging.

In the two defeats, Hinrich has been inexplicably undeadly. After a 3-for-13 clunker at Colorado, Hinrich made only 6 of 17 shots Saturday, missing 8 of 10 three-point attempts.

“I was getting good looks and shooting in rhythm,” a puzzled Hinrich said after Saturday’s Jekyll-and-Hyde performance by the Jayhawks, “and it wouldn’t go down.”

Hinrich had good looks because veteran Arizona coach Lute Olson dared the Jayhawks to shoot the Wildcats out of their zone defense. Kansas couldn’t. All the Jayhawks did was take their crowd out of the game.

Somebody asked Olson afterward if the ‘Cats’ comeback victory was attributable to tactics or to psychology. Olson, who didn’t just fall off a pickle truck, offered another reason.

“We made shots and Kansas didn’t,” Olson said. “That’s pretty simple.”

In fact, the Wildcats had one of their best shooting games of the season. Their field goal percentage was only .459 going in, but they hit 52.6 percent against the Jayhawks. Arizona’s free-throw percentage was a piddling .665, but the Wildcats made 22 of 26 charities Saturday for 84.6 percent. And Arizona was shooting 34.2 percent from three-point range, but made nearly 41 percent (9 of 22) against KU.

How many times over the years have you heard Williams say the first five minutes of the second half are the most important part of any game?

Well, the KU coach’s postulation rang prophetic Saturday when Arizona scored the first 10 points of the second half while the Jayhawks put up a three-spot of fours — bricks, turnovers and fouls. It made you wonder if the Jayhawks had used the halftime break to change into their nonmomentum uniforms.

“We got killed in the second half,” KU’s Nick Collison said. “That’s about all there is to it.”

Now the Jayhawks are in danger of rolling a turkey with still another Top Five team coming to town Monday night. Potential third-strike Texas is a lot like Arizona — quick, athletic and deep. There is a difference, though. Longhorns’ coach Rick Barnes is a stubborn advocate of man-to-man defense.

But will Barnes go to school on the Jayhawks’ zone woes against ‘Zona and scrap his standard man-to-man?

“If I was them, I would,” KU’s Langford said. “Why not? Rick Barnes is a smart coach. He’ll probably try some (zone).”

Right now, until the Jayhawks rediscover their outside shooting, KU’s foes will be zoning and Williams will be moaning and groaning.