CLEVELAND, Ohio -- Cleveland Cavaliers head coach John Beilein could see it.

His gifted young rookie, Kevin Porter Jr., who normally radiates infectious positive energy with a smile on his face, was visibly shaken.

So, about 30 minutes after Cleveland’s latest loss, before sequestering himself in the office connected to Cleveland’s home locker room and going through final postgame notes, Beilein made a detour. He stopped by Porter’s locker, patted him on the shoulder and offered words of encouragement, trying to lift the teenager’s spirits after a series of unfortunate and untimely late-game mistakes.

“I was telling him, ‘We wouldn’t have been in that situation to win if it wasn’t for the way you played tonight,’” Beilein told cleveland.com of his message during a brief chat in his office following the 115-109 loss. ‘”I know you will learn from it and it wasn’t you individually, it’s been a problem for all of us all year.’”

Porter was at the center of Cleveland’s turnaround, helping trim a 14-point lead to one various times during the fourth quarter. He scored eight of his 13 points in the second half. In more than 18 second-half minutes, the Cavs outscored the Raptors by one point with Porter out there, using him alongside Darius Garland, Collin Sexton, Larry Nance Jr. and Kevin Love in a new closing lineup that at least one player who spoke with cleveland.com “really liked.”

But the rookie giveth and the rookie taketh.

He committed a career-high seven turnovers in 29 minutes. Three came in the fourth quarter, two in the final 40 seconds that kept the Cavs from making one final push.

“I usually do better taking care of the ball,” Porter said. “I don’t recall ever having seven turnovers in a game before. It was definitely different for me, but it was a learning experience. I’ve got my guys here to talk it over with and we’re going to go out and next one, I’m not going to have seven. I start with zero next game and we’re going to go out there and try to get a win.

“Just learning experience. I’m young, it’s the first time, second time I’ve been in that position in crunch time to make plays and be a facilitator. It’s just a learning experience. I’m young, first year in the league and I’m going to see more moments like that.”

Even though Porter didn’t come through late Thursday night, Beilein said he won’t hesitate to call on him again Saturday night versus Golden State if the Cavs are back in that position. Beilein will put the ball in his hands because Porter has proven -- in just a short time in his burgeoning NBA career -- to be an adept passer and one of the few left who can consistently create quality looks on the offensive end. Sometimes his own shot. Other times for teammates.

“That’s one of the missions this year is for him to learn how to play in those situations,” Beilein told cleveland.com. “I don’t know what his minutes were like at USC, whether he was in crunch time sometimes, I’d assume he was, but he might not have been. It’s good to learn. It’s really learning on the fly. I think handling that adversity is one of the first steps in being a champion. Just being able to fight through it and forget about it. Too many guys will spend too much time and they just have to move on. It’s a suitcase you carry when you are worried about it.”

Beilein felt Porter handled that private postgame chat well.

“He said, ‘Coach I’m good. I know exactly what you’re talking about.’ It’s always good and it depends how you approach these things. But I’ve never looked at a turnover late in a game to cause us to lose a game,” Beilein said. “There could be two or three in the first quarter that were crazy and I’m sure there were tonight too. That can cost the game too.”

While Porter was the ringleader, the Cavs finished with 23 turnovers Thursday night. Their goal before every game is around 13. Beilein feels that’s an acceptable number. But 23? And averaging 16.4 on the season, the league’s second-worst mark? It’s really tough to overcome that many empty possessions on a nightly basis.

There were plenty of growing pains Thursday night. For Porter, Garland and Sexton. For everyone. But there were also some encouraging signs. Porter being on the floor in those late-game moments was one.

On Dec. 23, the Cavs sent Jordan Clarkson -- a staple of the closing group -- to the Utah Jazz in a move that was mostly about the future. The Cavs added Dante Exum and a pair of second-round picks in that deal. They were also throwing support behind their exciting teenager who appeared ready for a grander stage -- just like Thursday.

“We’ve just been building this the whole season,” Porter said. “Individually I’ve been just trying to get better each and every game. My role on the team is just do whatever I can. Literally whatever I can. Of course it’s confidence being in there late, but you know I’ve got to make better decisions down the stretch.”

The first questionable decision came with the Cavs down by four. Toronto swingman Norman Powell had just buried a clutch corner 3-pointer that gave the Raptors a two-possession advantage and hushed the crowd with about a minute remaining. Sexton tried to answer, bricking a pull-up jumper from the foul line. But Love grabbed the offensive board and flung a pass that was slightly off target to Porter, who gathered, looked at the rim and seemed ready to launch. Only he hesitated with Toronto guard Fred VanVleet closing out.

So, Porter took a few dribbles, pulled back, thought about shooting again and then threw a pass that was stolen by Powell. As a few teammates slumped their shoulders, Powell sprinted ahead and threw down a one-handed dunk that put Toronto ahead by six.

Porter made a shooting motion all the way to the bench. He continued flicking his wrist, his way of letting everyone nearby know he recognized the error.

Less than 20 seconds later, following another Cleveland timeout, the Cavs put their trust in Porter once again, having him throw the sideline inbounds pass. Inaccurate, the ball sailed wildly over Nance’s head and out of bounds. Another mistake. Porter smacked himself in the head repeatedly after that one. That was the Cavs’ final chance. They squandered it. Add it to the list of late-game bobbles.

“He’s a player that wants to get better so we know he will learn from it, but it’s just one play at the end of the game,” Love said. “We, overall, need to get better at executing so it wasn’t that. That’s not what cost us the game, but that’s a growing experience for us and we love the way he’s playing. He’s incredibly talented and at his age he’s only going to get better and better in leaps and bounds.

“The good news is I like they are frustrated because they want to shine and want to have great plays and make plays at the end, but sometimes it’s like that. There’s a lot of learning experiences for everyone involved.”

It’s been tough to accept at times, but that’s what this season is about. Those are the competitive situations the front office envisioned when dealing Clarkson, when shifting into player-development mode. There’s only one way for Porter, who is rapidly becoming one of the brightest lights during this gloomy rebuild, to gain that in-game experience.

Putting him in those spots, maybe even feeling the sting of failure, will eventually benefit the Cavs. At least, that’s what they are hoping.

“History teaches us a lot,” Beilein told cleveland.com. “If he learns from this game then it’s going to help us in the future. Here, with what we’re doing, it’s so much about the future.”

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