Let's talk about the process of teaching things in football. Whether it is a blitz or a new pass pattern, there is many different processes that coaches go through to teach it. Many coaches differ in how they go about teaching but let's talk about some things that are done when installing a concept.
Let's talk about the install of a pass concept. First you would hand out a sheet diagramming the play usually drawn up on a computer program with any descriptions written in. This would usually be drawn on a football field and would show where the receivers align in relationship to the landmarks on the football field - hashes, sidelines.
The coach sometimes will then draw the play on a dry erase board or smart board versus the three top coverages you are expecting, talk about the releases and adjustments against various coverages if they are any. Some teams change routes on the fly based on coverage looks.
A video would then be shown of this concept if it has previously been run so the players can see it being executed in a game situation. Also, the coach would put up defences the opponent has shown that would help the players visualize the success of the concept.
When you get on the practice field you will usually walk through the concept and the alignment on the field, and a little later the play will be practised full speed with the quarterbacks and receivers to get the exact timing and drop mechanics down for the QB. The play will then be practised against the defense allowing the receivers and quarterback to work against other players who are reacting to them and the football. Sometimes this play will also be run in a team session with all twelve players to make sure the protection is timed up and worked on.
After practice the coaches will then review the film and analyze the execution of the pass concept and take notes for their players about the play. The following day in meetings the players will be able to see all the repetitions of that pass concept and see video of themselves practising it.
As you can see that when you have many players, you always have to cover your bases on how you teach them. So people have to see it in a classroom others need a walk through to understand and some players have to rep things many times. I have coached a few players that can execute with little or no practice.
Repetition is, I believe, a key for being able to do things well. As you can see, coaches go to great lengths to install the plays you see on the field on gameday.