"I committed to Stanford," said Gaffney.
Gaffney was admitted into Stanford earlier this month, paving the way for the state player of the year to head to Palo Alto.
When he told the news to Jim Harbaugh, Gaffney said he was thrilled to hear it.
"Coach Harbaugh loved it, he was fired up as can be," said Gaffney.
The football-baseball star will play both sports at Stanford, and the whole package Stanford presented was the difference.
"Everything about it felt perfect," said Gaffney. "I'm playing both sports in college and I talked to Toby Gerhart all about that."
Gaffney helped lead Cathedral to the CIF-San Diego Section D-III title then followed it up by helping leading Cathedral to the California State D-II title, with a five-touchdown performance in the finals.