Farmer had been vocal about his desire to play receiver at the college level, and the recent transfer of two of the Trojans' top five receivers apparently helped USC coach Lane Kiffin make his decision.
The 6-foot-1, 205-pound Farmer was a highly-touted prep prospect who came to USC out of nearby Gardena Serra, where he was teammates with Trojan receivers Robert Woods and Marqise Lee. Farmer spent the first half of his freshman season in 2011 redshirting as a backup receiver but moved to running back midway through the year.
He ended up playing in four games at that spot, carrying the ball a total of five times for 15 yards and catching four passes for 42 yards.
In November, after two of his four appearances, Farmer told ESPNLosAngeles.com that he wasn't picking up everything at running back as quickly as he'd hoped.
"I would like to move back to wide receiver," Farmer said at the time. "Obviously I am still more comfortable playing that position. But my plan is to play this season out and then re-evaluate my situation with the coaching staff going into spring ball."
USC has had three running backs or receivers announce plans to transfer in the last two weeks, including Amir Carlisle, Kyle Prater and Brice Butler. Carlisle is transferring to Notre Dame and Butler is heading to San Diego State; Prater has said he will be picking a school closer to his hometown of Chicago.
Spring practice is scheduled to begin for USC on March 6. Farmer will begin the month-long practice sessions in competition for the No. 3 receiver spot behind Woods and Lee, but he'll also be on close watch off the field.
The team source also said Farmer is on academic probation at USC for the 2012 spring semester, meaning the 19-year-old recorded a GPA below the minimum of 2.0 in his first college semester last fall.
If Farmer again records a sub-2.0 or does not raise his GPA past the 2.0 threshold with his spring performance, he stands to be academically ineligible for the 2012 season. Student-athletes must normally record two consecutive below-the-minimum semesters to be ineligible -- as such, it is rare to be academically ineligible as a second-semester freshman.
USC has had only one such case in recent memory: running back Joe McKnight's, and his situation was caused by the mid-semester dropping of a class during spring practice.
Farmer did not immediately respond to a request for comment Friday night. A USC spokesperson said he could not comment on players' academic statuses with the team until closer to spring practice.
Pedro Moura covers USC for ESPNLosAngeles.com.