Luckily Drew posts all his workouts to strava and I follow them very closely. My conclusion is he is an insane talent. It is amazing how well he runs based on what he does. His training is what you would expect from a 14-14:30 guy.
Go through his strava. It is a bunch of 5:00ish threshold and mile pace 200s. Which are fine to get good, but it just lacks the raw intensity to get great. Look at the most succesful groups in the US right now- BTC and On, they are known for absolutely brutal workouts. This was always my criticism of Tinmans training, at some point you need to do the brutal fast fast work to really make the jump.
The problem is not the trainign thought. Drew can not workout very hard/high mileage (in comparison to his peers) without getting hurt. He has been running 80 mpw the last months and this is the most mileage he has ever run.
I think the answer is to just keep what he is doing but try not to get hurt and miss months at a time. He obviously has insane talent still but regardless of who you are if you miss 2-3 months every year you won't be great.
I (like many others) believe switching groups would be a great move. But if he gets injured immediately there is no point.