"See what happens when you don't play with a sense of urgency?" it read.
A night later, despite a slow start, Capel's Sooners avoided the upset bug in their season opener with a 71-55 win over the University of San Francisco in the first round of the 2K Sports College Hoops Classic at Lloyd Noble Center.
OU will play Denver, a 76-75 winner over East Central University in Thursday's first game, at 7 p.m. Friday night in the regional final. The winner will move on to play Nov. 15 and 16 in championship round games at New York City's Madison Square Garden.
"All of those things got our guys' attention," he said.
San Francisco took care of the rest.
As Capel looked on, the Dons took a 25-20 lead with 9:53 to play in the first half on a 3-pointer by Danny Cavic. It was San Francisco's inside game, however, doing the damage against the Sooners' man-to-man defense.
"We thought we could work the inside against their inexperience," Don coach Jessie Evans said. "Dior is a very clever player."
But as soon as the Sooners switched to a zone, the inside advantage was gone, and almost instantly so was San Francisco's lead.
Dior's jumper at 8:23 put his team up 27-23, but the Dons wouldn't score again for nearly seven minutes. OU used a 17-0 run getting a number of easy buckets from its defense.
"The zone really kept us in the game; we were really active in it," Capel said. "And what I loved during that stretch is how much emotion our guys showed toward each other."
The run was capped by an Austin Johnson alley-oop to Griffin, who flew high above the rim before throwing it down to the delight of the 8,219 in attendance.
Though it was his first official game, Griffin has already become known for his dunking prowess through six exhibitions. And he's well aware of it.
"I know it not only gets the team and crowd into it, but it focuses me a little more. It makes me work a little harder on defense because I want another one," he said.
Despite the early troubles slowing Lowhorn, Griffin was more than a load to handle himself, scoring 12 points and grabbing 10 rebounds by halftime as the Sooners built a 10-point lead.
"He's like a locomotive that turns into one of those Eurorails," Evans said of the 6-foot-10, 243-pound Griffin. "He comes at you full steam ahead and then all of the sudden there's this smoothness."
Griffin finished the night with 18 points and 13 rebounds, both team highs.
"I was semi-satisfied," he said. "I definitely need to play harder every possession. I have to keep my intensity up every play and I have to be able to do that for a full 40 minutes."
Blake's older brother, junior Taylor Griffin, added 13 points and six rebounds. He started alongside his sibling.
"It felt good. I felt at home," he said about starting. "I thought I was able to bring energy to the team and I know that's going to be one of my biggest roles this year."
Tony Crocker added 10 points for the Sooners, who shot 51.7 percent in the first half and 48.2 for the game.
San Francisco, which was shooting near 60 percent for the game's first 12 minutes, was limited to 36.8 percent overall.
"They turned it on and we weren't able to get over the hump," Evans said. "They just keep coming at you and that makes it tough, especially on the road.
Lowhorn finished with a game-high 26 points.
Notes: Starting for the Sooners were both Griffins, freshman Cade Davis, sophomore Tony Crocker and junior Austin Johnson…OU won the rebounding battle, 35-34. The Sooners had 11 offensive boards, but gave up 13…OU had 16 assists against 12 turnovers. Johnson led the team with seven assists without a turnover…OU wasn't sharp from beyond the arc, shooting 23.5 percent (4 of 17) on 3-pointers…The biggest lead enjoyed by OU, 20 points, came at 2:48 of the second half…The Sooners had 36 points in the paint, 13 points off turnovers, 14 second-chance points, eight fast-break points and their bench outscored San Francisco's 17-8.