Usually, teams like Clemson that clobber opponents with relentless defense and shorten the game with long possessions are safe with a big lead.

For some reason - maybe inexperience, maybe complacency or maybe dumb luck - lately, the Tigers were tight when their paw was on the other team's neck. And they just couldn't twist.

A 13-point headstart briefly into the second half wasn't insurmountable, as SMU stormed back to stun Clemson 65-59 Tuesday night in an NIT semifinal game at Madison Square Garden.

Unlucky 13: the biggest balloon popped, the largest lead surrendered by the Tigers this season. Clemson coughed up a double-digit cushion in three of its final four losses, leading by 10 at Wake Forest and by 11 against Pittsburgh in ACC defeats.

Clemson did not trail in the first 35 minutes of action Tuesday.

"Moving forward, I think we have to learn how to play with a lead," said junior point guard Rod Hall, whose 18 points led the Tigers. "A few games we had a lead in the first half, we kind of came out sluggish, and teams got after us and made baskets we shouldn't have given up."

The Tigers' season extended into April for the first time in school history, but they were eliminated a game short of their goal. Clemson finished 23-13 on the year, a 10-win improvement from last year's squad.

"We have some young men in our program that made huge strides this year and have become good players," Clemson head coach Brad Brownell said. "Now if you're gonna take the next step, you need more guys to be great players."

Clemson had one of those this year, and K.J. McDaniels, pegged as a late-first-round NBA draft prospect, doesn't yet know if this was his last game in an orange and white uniform. If it is, the junior's 11-point, 7-rebound, 3-assist, 3-block line wasn't memorable, but his 2013-14 campaign sure was.

"I'm just still in shock. I still have a lot of improvement I can (make) for myself," McDaniels said. "So (the NBA decision) is not something I'm really thinking about right now."

Warming up to a primetime TV audience, the Tigers were scorching in the first half, shooting 56 percent - capped by Damarcus Harrison's 3-pointer before the buzzer, giving Clemson a 38-26 lead at the break.

Strange stat: the last three games in which Clemson shot better than 55 percent in a frame, the Tigers lost. Doesn't help to shoot 24 percent in the second half, which the Tigers did against the refocused Mustangs.

"The first half, Clemson did about as well as any team we've played against. They controlled the tempo, they had much more energy than us, they executed great," SMU coach Larry Brown said.

"We didn't have much to say at halftime, except that we had to match their energy. I thought that was the best half we played all year."

SMU will battle either Minnesota or Florida State in Thursday's championship game.

For their part, the Mustangs (27-9) shot a sizzling 59 percent after halftime, outscoring Clemson 37-18 after McDaniels' 3-pointer with 19:02 remaining.

The Tigers made seven of their first 10 3-point tries, but missed nine of their last 10.

"Unfortunately, we saw the second side of our team a little bit this year," Brownell said. "We struggle offensively at times, and we just didn't shoot the ball very well in the second half."

SMU forward Markus Kennedy dominated the paint, with a game-best 21 points (8-13 FG) and nine rebounds. The Mustangs outrebounded the Tigers 35-25, as once again the absence of injured forward Jaron Blossomgame left Clemson shorthanded on the glass.

"I felt like you could tell a difference when he's not out there," McDaniels said. "He's a big, big factor to the team."

McDaniels had three blocks, giving him 100 for the season - just the third Tiger to swat a hundred. That included a straight-up swipe of a layup attempt McDaniels cradled on the way back down, one of many impressive blocks on the year.

If McDaniels answers the prayers of the final Littlejohn Coliseum crowd of the year - home fans chanted 'One More Year' before last Tuesday's NIT quarterfinal win over Belmont - Clemson conceivably returns every rotation player in 2014-15.

If McDaniels decides it's time to go pro, there remains plenty of somewhat-proven puzzle pieces. But somebody will have to step up and replace McDaniels' 17 points and seven rebounds per game.

"We just need a little more consistency from a few more guys," Brownell said. "The good news for us is we have all young players. This is a tough process, but certainly the experience of the last two weeks and the grind of the season has helped us."