USC will have five scholarship quarterbacks, including two freshmen, on its roster in the fall.
San Clemente High quarterback Sam Darnold will be the fifth to join the group, but said after the Army All-American Bowl that he has no reservations about his commitment.
"My thought, from the beginning, really, was that I'm going to have to compete wherever I go for the starting job," said Darnold, who committed after Ventura St. Bonaventure's Ricky Town.
Darnold completed six of seven passes for 89 yards, including a 63-yard touchdown, but had a pass intercepted and returned for a touchdown. He rushed for eight yards in two carries for the East team in a 39-36 loss to the West.
San Clemente Coach Jaime Ortiz said Darnold has the "things necessary to be successful at the next level."
"It's hard to describe, but he has it," Ortiz added.
USC will host Darnold on an official visit Jan. 16.
Chris Foster contributed to this report.