Walt Daniels, 66, died at 2:30 a.m. Tuesday at Sharp Memorial Hospital, the San Diego County Medical Examiner's Office said.
Daniels appeared to sustain a head injury after falling about 25 to 30 feet out of a booth that was to be used by Broncos assistant coaches, and landing on the loge level. He was administered CPR before being taken to the hospital.
Workers later cleaned up a puddle of blood.
The accident happened about three hours before kickoff and delayed the opening of the gates by about 40 minutes.
"The San Diego Chargers' family is greatly saddened by the loss of Walt Daniels," the team said in a statement. "Walt loved the team and loved working in the press box on game days for more than 20 years. Our prayers are with his family and friends during this most difficult time."