The thing about Custom PB's is that only certain plays are recognizable as each of the 4 formation audibles: quick pass, run, deep pass, and play action. If you were to put one run play for a certain formation in your pb it would by default by your run formation audible. However, certain plays hold precedence over other plays. This is true for each of the 4 formation audibles: quick pass, run, deep pass, and play action.
For strong close I have noticed that the dive holds precedence over any other run play then off tackle comes next. Pretty much im saying that you if you put every run in strong close in your custom pb, the dive would be your run audible, take dive out and the off tackle would be your run audilbe, and so forth.
Its something you have to play around with to figure out. I spent one of my free nights going over how the formation audibles work and found a lot of stuff. The big thing to keep in mind is that most plays from you pb you probably wont use anyway. Only put the plays in that formation that you use. I try to limit the plays in each of my formations to the bare minimum.