By JOE REEDY
AP Sports Writer
COSTA MESA, Calif. (AP) — The Los Angeles Chargers are set with Austin Ekeler as their lead running back. Trying to find a dependable backup has been a work in progress the last two seasons. With recent draft picks Joshua Kelley and Larry Rountree struggling to adjust to the NFL, and Justin Jackson a free agent, the Chargers are hoping fourth-round pick Isaiah Spiller can come in and provide a boost. Spiller was on the practice field Friday for the start of rookie minicamp. Most of his time was spent in individual drills with running backs coach Derrick Foster.