The phrase of the day is “Max Protection”. Max Protection is a protection call where usually only 3 players go out for a passing route. There are normally two ways in which this can be accomplished.
1) The offense can call a play from the huddle/sideline that includes max protection where only 3 routes are run by receivers.
2) The QB can also audible and:
a) change an assignment,
b) shift a protection or
c) kill routes so that only 3 men go out for a pass.
The other two, usually a RB or TE stays in and blocks in pass protection. “Max Pro” is an abbreviated form of the phrase.
If a QB is reading an overload on one side of the ball, then he can kill a route to have the TE stay in and help with the overload. He can also move a player to the opposite side of the formation to help with that.
An overload is when a defense loads up one side of the offense with pass rushers or blitzers with more defenders than offensive lineman. At times the OL can shift their call to the protection, which is one reason why you see the Center and or QB saying “#52 is the Mike”. That is centering up the defense from an offensive perspective so they can apply their rules/calls.