Yet another difference in hiring Bill O'Brien vs a first time head coach is that he has been prominently involved in numerous coaching clinics over the years. The following series dates back to his Penn State days but also touches on his time with New England, Houston and Alabama. They are very insightful into his personality and how he will run an offense, a coaching staff and work with his players.
It is also clear that he likes empty set formations a lot. That is very exciting with Castellanos, especially if TC has the green light to run if no one is spying him.