The shooting guard scored 29 points for the Golden State Warriors in the first half of a Western Conference semifinal game against San Antonio earlier this month. He finished with 34 points, 14 rebounds and three steals in a victory.
Someone in the family wanted more, though, and you probably don't need two guesses if you're even vaguely familiar with the Thompson family's picky patriarch.
Never mind that according to the Elias Sports Bureau, the only other starting guards to match Klay's scoring and rebounding totals in a playoff game in the last 25 years were Michael Jordan, Kobe Bryant and Vince Carter.
According to Mychal Thompson, his son should have scored 40 points — because he missed too many layups.
These are the perils of being the offspring of a two-time NBA champion and Lakers radio analyst whose expectations are always high.
Yet Klay doesn't wince whenever his cellphone rings.
"It's good to hear from him," said Klay, a former Santa Margarita High standout. "It's great to go to him for advice."
Mychal has dispensed plenty of that throughout a best-of-seven series that resumes with Game 6 on Thursday night at Oracle Arena in Oakland with the Spurs holding a 3-2 advantage.
There have been times when Klay has not at all looked like a 23-year-old making his first foray into the playoffs in only his second NBA season. He has been the splish to Stephen Curry's splash, making shot after shot as the up-and-coming member of the duo known as the Splash Brothers.
But there have been other times when his contribution has slowed to a drip, his shot betraying him and San Antonio's Tony Parker repeatedly driving past him for layups, as Parker did during a 32-point outburst in Game 3.
"Klay came out and was deferring in Game 3," Mychal Thompson said. "In Game 2, he came out on the attack, and that's the difference in the games."
Klay was at his best in the series' first two games. He used the length that accompanies his 6-foot-7 frame to play lockdown defense on Parker while helping the Warriors take a 16-point lead late in Game 1. They squandered the advantage only after Klay fouled out with nearly four minutes left in the fourth quarter of an overtime defeat.
After brooding over what he perceived as letting his teammates down, Klay responded by making eight of nine three-pointers in Game 2.
"I made a lot of new friends that night," he said. "Half of those people texted me after" the game.
Mychal's voice has remained constant after victories and defeats, and it's been mostly reaasuring even as Klay's production dipped to 17 points in Game 3, 10 points in Game 4 and four points in Game 5.
"It's a blessing to have somebody who's been in the playoffs, been in difficult situations, had good games, had difficult games, all those factors," Golden State General Manager Bob Myers said of Mychal Thompson, who won titles with the Lakers in 1987 and '88. "To be able to talk to your father about something like that and someone who's had that experience is a big positive."
Mychal's messages tend to be upbeat, if occasionally tinged with subtle jabs that Klay knows not to take personally.
"He thought I played great 'D' on Tony and Manu [Ginobili] in the first two games," Klay said, "but the thing is, it's a very humbling league. In Game 3, you're high on yourself, you think you're playing great defense and Tony Parker goes out and gets 25 in the first half."
Klay has always been able to make shots; it's his improved defense that has made him one of the best young players in the league. His feistiness sprouted from backyard battles against older brother Mychel, who played briefly last season with the Cleveland Cavaliers, and younger brother Trayce, a center fielder with the double-A Birmingham Barons, a Chicago White Sox affiliate.
Presiding was Mychal, who as a 6-10 center-forward was the first pick of the 1978 NBA draft, and mother Julie, a 5-10 former setter for the volleyball team at the University of San Francisco.
"His mom and dad were always there, not just for him but for all three boys," said Jerry DeBusk, who coached the Thompson brothers at Santa Margarita. "They were just classy, and dad didn't interfere too much and his mom was always supportive."
Mychal also was openly critical when he felt it was necessary. He ripped his son on the radio during Klay's junior season at Washington State after the Pacific 10 Conference's leading scorer was cited for misdemeanor marijuana possession.
Earlier this season, Mychal said he controlled his son's finances and would dock his allowance after Klay was fined $35,000 for shoving Indiana's Roy Hibbert during a fracas involving Golden State's Curry and David Lee.
Mychal later said he was joking about the finances — but not before Klay's friends and teammates teased him about it. It's a good thing Klay laughed right along with them.
"I just got a kick out of it," Klay said.
He's usually not smiling when he receives his dad's text messages about staying out of foul trouble. Mychal was able to provide his thoughts in person after attending Games 3 and 4 in Oakland.
After Klay made two shots in the final minutes of regulation and a key steal in overtime during the Warriors' 97-87 victory in Game 4 on Sunday, father and son met briefly in a hallway deep inside Oracle Arena.
Mychal praised Klay's defense and told him he was proud of him. Oh, and one other thing.
"Call your mother," Mychal said, making sure Julie was not forgotten on Mother's Day.
Mychal, who doesn't like to travel when the Lakers are out of season, has vowed to make an exception for his son under the right circumstances.
"I told himto 'make me go on the road again, make me go to Memphis' " for the Western Conference finals," Mychal said. "Memphis will be worth it."
Indeed it would, a rare instance in which Klay has the final say.