The first day of training camp this summer saw Javontee Herndon, the wide receiver who helped spark the Chargers' punt return game in 2015, field a welcome-back punt on a warm, morning practice.
He ran after the catch.
He cut on his left knee.
Pop.
The second day saw wide receiver Stevie Johnson, a route-running whiz whose technique is such that some teammates incorporate elements of it into their own, run a shallow route in a 7-on-7 period. He dove for a pass. He popped to his feet. Then, he limped, hopped on one leg and fell back to the ground, clutching his right knee.