Alex Singleton there for the Broncos. >> On the field, Broncos linebacker Alex Singleton looks unstoppable. >> Singleton battled the big tight end.>> He's the team's co- captain and leading tackler. >> Singleton ripped up through the catch. >> But just weeks ago, a surprise setback took him out of the game.Singleton telling reporters in a conference call, >> "It's been a whirlwind." >> It started with a letter left in his locker. A routine NFL drug test finding elevated levels of a hormone called hCG, which ...