Reading the Chargers' board, there is speculation that the decision to play the starters in a meaningless game was not Staley's. Along with analytics, he is big into sports science. He doesn't play starters in preseason and doesn't practice on Wednesdays because he doesn't want the players' bodies to take the abuse and is big into resting players rather than getting additional reps. So either the players wanted to play because of contract incentives or Spanos forced his hand. I have no idea if this is true, but that's what they're saying.
They also get into the endless debates about QB rankings and feel that Herbert is disrespected. For some reason, Josh being ranked above Herbert is the one that get's under their skin the most.