[TekeRam]

I think it means that there's no set progression for recievers. Meaning that it's up to Bulger to determine in the presnap what will be his progression for that play, based on who looks like they'll be open according to what the defense is showing.

In other words, as opposed to a certain play's progression always being Holt, McMichael, Jackson, there's no order and whoever is open should get the pass, as long as Bulger sees him.