Raiders rookie QB O'Connell hopes to continue journey from walk-on to starter despite being third on depth chart

Raiders rookie QB Aidan O'Connell was a walk-on at Purdue.
O'Connell hopes to continue his journey from walk-on to NFL starting QB.
O'Connell is currently third on the Raiders' QB depth chart behind Garoppolo and Hoyer.
Garoppolo's injury history means O'Connell must stay ready to play.
At Purdue, O'Connell rose up the depth chart and set passing records.