Whch basically tells the other team you're getting ready to run the wildcat on this play, making it useless...
You gotta sub in some guys to run it anyway, and as soon as you break the huddle, the D knows anyway, and can adjust.
You can change your defensive groupings if you see the starting qb coming off the field for the backup. It's too late when the QB is headed wide right.
I would just motion the QB all the way off the field. Pennington goes in motion. Brown takes the snap and Pennington heads straight for the gatorade.