Bills nickel corner Taron Johnson might have looked around during Thursday’s practice and been struck by what he saw — or to be more precise, what he didn’t see. None of the Bills’ top four other defensive backs were on the field. That’s counting Pro Bowl cornerback Tre’Davious White, who hasn’t played since tearing his ACL last Thanksgiving. Dane Jackson was looking on from the sidelines, days after being released from the hospital for a scary neck injury against the Titans. Veteran safeties Micah Hyde and Jordan Poyer weren’t practicing, either. Hyde hurt his neck late in Sunday’s game and Poyer was nursing a sore foot.