San Diego State retired the No. 19 worn by coach Tony Gwynn, who died of cancer in June.
The ceremony was held Friday night before the Aztecs played Valparaiso in the season opener.
Chris Gwynn said two of his brother's best traits were humility and selflessness.
"I know he knew he had a big effect on people, but I don't think he understood how great it was," Chris Gwynn told the crowd at Tony Gwynn Stadium.
"I know he's looking down at us, I know he's laughing that laugh, saying, 'This is great; I'm glad you're honoring me,' but he's also saying, 'It's time to play ball.'"
Gwynn coached the Aztecs for 12 years after his 20-season, Hall of Fame career with the Padres.
Gwynn played basketball and baseball at SDSU. He was 54 when he died.
