Prosperity, as it turned out, was fleeting for Seton Hall. Just like the Pirates’ 12-point first-half lead Saturday and their nine-point edge in the second stanza.

Such is life for a young team finding its way in this minefield of a non-conference schedule coach Kevin Willard formulated.

Seton Hall showed its youth and was unable to finish off a quality opponent that was ripe to be put away. As a result, the Pirates couldn’t build off their impressive Wooden Legacy title from last weekend, suffering a bitterly disappointing 70-65 loss to Louisville in front of 8,505 at Prudential Center.

“Getting this group to understand time and score, and opportunities, there’s no better way to do it [than] against these teams,” said a clearly frustrated Willard, who was uncharacteristically short with the media in his postgame press conference. “They made good plays and we didn’t.”

There was the big lead early, a 19-7 edge just 7:17 in, and a 52-43 advantage with 13:52 left in the second half. But on each occasion, a few loose possessions cost the Pirates the chance to pull away, whether the result of bad shots, missed defensive assignments or being a step slow to a loose ball.

The biggest problem was the 8:14 stretch of the second half in which Seton Hall (4-3) managed just a single field goal, allowing the Cardinals (5-2) to take control, turning a five-point deficit into a four-point lead.

Before Myles Powell’s 3-pointer with 1:59 left, Seton Hall missed 19 of 21 shots, many of them contested drives or forced shots late in the shot clock. They mostly weren’t high-percentage attempts.

“It’s frustrating,” sophomore forward Sandro Mamukelashvili said. “We’re a young team. Every time it comes down to the wire, I feel like everybody’s a little stressed. So we’ve got to chill out a little bit, trust each other more.”

The Pirates still had opportunities late. With a chance to go ahead with just over a minute left, Myles Cale missed an off-balance runner in the lane on a disjointed possession and Ryan McMahon drained a crushing 3-pointer with 33.6 seconds left to push the lead back to four.

Powell scored a game-high 23 points, but was just 2 of 12 from the 3-point line, and Willard said he felt some of the attempts were forced. Mike Nzei added 12 points with six rebounds, but the senior forward didn’t have many opportunities late. That, Willard said, needs to change. Seton Hall was too reliant on the drive.

The final minutes were similar to the end of the loss at home to Saint Louis and the win over Miami in the Wooden Legacy final. With Powell hounded by double teams, someone else needed to take charge. It didn’t happen. In previous years, Seton Hall had several late-game options. Right now, there’s only Powell.

“I think the biggest thing is other guys have to get a little bit more confident in the fact that they’re going to have to make a play,” Willard said. “[Quincy McKnight] got to the rim twice, Myles Cale got to the rim three times.

“It’s obviously tough, because you want your main guy to have the rock, but those guys have to continue to get confidence that they’re going to get opportunities to make plays.”