SAN FRANCISCO — The Herald has learned the reason behind Jayson Tatum’s come-to-life 18-point outing in Wednesday’s 113-102 victory over the Clippers.

The performance came on the heels of his malodorous 1-for-6, four-point post the previous evening against the Lakers, and the connecting factor is that Tatum’s less than 2-month-old son, Jayson Christopher Tatum Jr. was in attendance for both games.

Clearly, big Jayson didn’t want the child thinking his dad was a bum.

“Yeah, something like that,” said Tatum with a smile.

(Young Jayson was not available for comment as he rested in his grandmother’s arms Wednesday.)

The 18 points were five more than Tatum had scored combined in the previous two games. His shot had been uncharacteristically shaky as of late, and, worse, the assertiveness that had him looking like anything but a rookie early on had waned.

It hasn’t been so much that he’d hit a rookie wall, but the confluence of events was no doubt creeping into his picture.

“I didn’t expect this — to be 19, be a rookie, playing this much and having a kid,” Tatum said. “It’s a lot, but, I mean, I’m enjoying it.

“I haven’t been playing that well, and I took it upon myself to just try to be more aggressive and contribute more.”

It also had to sting the third overall pick that Kyle Kuzma, the No. 27 choice, led the Lakers with 28 points on Tuesday. But according to Brad Stevens, there is a larger issue at play.

“It’s a hard league. That’s one of the great lessons for a guy his age is you start to realize that you’ve got to do it every night,” said the coach, drawing out the “e-e-very.”

“And it doesn’t stop. It just keeps coming at you, and I think it just makes him and others appreciate Kyrie (Irving) and people like that even more, because it’s every night.”

The spotlight will be even brighter than in Los Angeles when the Celtics meet the Warriors in Oakland tomorrow evening, and Tatum could only nod when apprised of Stevens’ comments.

“You’ve just got to bring it every night,” he said. “And that’s what makes the great players great.”

Right now the Celts need Tatum to be better than good. Wednesday’s win snapped a four-game losing streak and kept them atop the Eastern Conference standings, but Golden State awaits, and the trip closes out in the altitude of Denver Monday night.

“That’s what we need from him,” Irving said after the win over the Clippers. “Yeah, we just need him to be like that, just have that aggressive mindset.

“I’m here to remind him of that throughout the game, throughout the season. Just take advantage of the opportunities that he’s afforded out there offensively and defensively. He can make a huge impact, and I think he’s aware of that.

“As a developing young player, the best thing he can do is just continue to learn how to be consistent. It’s a trait that you have to develop over time, and I think he’s doing a great job of kind of learning on the fly.”

It hasn’t helped Tatum that the Celtics offense has been a tad queasy overall of late. There was very good ball movement Wednesday, but too often the C’s have been slow to spots on the break and have been stagnant in the halfcourt.

Tatum excelled early on in large part because he was taking advantage of openings created by others — extra attention to Irving and Al Horford — and general unselfishness that pulled defenses out of position.

But Stevens believes Tatum and his mates need to be able to overcome that, or at least nudge the club out of such ruts.

“We have a lot of talks about how we can all play better together,” Stevens said, “but also how we can impact the game with corner crashes, cuts.”

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LeBron James was reunited with former Cavaliers teammate Irving in the NBA’s first All-Star draft. James made the selection.

As for Irving’s teammate from the Celtics, Horford was picked by Stephen Curry. The draft was not televised, and neither James nor Curry revealed who they chose first.

James and Curry will be the captains Feb. 18 in Los Angeles for the first NBA All-Star Game that doesn’t use the Eastern Conference vs. Western Conference format.