I love how there is a comment form, but you have to be logged in to make a comment AND there is no place to create an account or log in. That's exactly what blogging is all about [sarcasm].
Here is the comment on the Head Coach play creator I was going to post:
I'm going to guess that the inability to do some of those things is related to reducing the amount of AI trickery usually involved in creating your own plays. I go way back to Sierra's FBPro96 and it was heavily about creating your own playbook. There are so many easy ways to game the AI that the "rules" became quite ridiculous. Putting receivers in motion was one of the easiest. The defensive assignments change on the fly and that's when you could make things happen that created "glitches".
If EA thought of those things in advance then I'm impressed.