I think that there are several major reasons why Mr. Ritzenhein has not yet run sub 2:10.
It's probably very frustrating for Mr. Salazar that he has not yet coached one of his athletes to a sub 2:10 in the marathon.
Based on my own experiences, doing massive sets of mile repeats and really hard long runs is a recipe for disaster. Mr. Salazar needs to focus more on longer moderate efforts at 40-50km so that glycogen is spared during the race. One every one of my marathon PR's since college, I've run at least one run of 28-30 miles, at about 6:00/mile. The late-race strength that you can derive from this sort of training is significant. The key is being careful with the pace.
I think that they are throwing way too many "gadgets" at him like the underwater treadmills, cryotherapy chambers and the like, and worrying way too much about his running form. I've seen videos of him in college, and his form is smooth and efficient. As we've seen with other world class runners, like Mizuki Noguchi, tweaking someone's running form can be disastrous.
I will never forget 2 years ago when I did a really hard 10x1mile in Austin Nevada (7000 feet alt) about a week before the Montreal Marathon. I felt really great in the first ten miles of the race, then it was a slog getting to the finish line, but I still finished 5th. The last 10km was hell.
Mr. Ritzenhein is no doubt one of the most talented runner in the USA and the world, and I think that with some slightly adjusted training methods, he can run 2:06 or 2:07.
If I were Mr. Ritzenhein, I'd forget about running any indoor track or anything, and start getting ready for London, Tokyo or Rotterdam. I hope that he runs a good one!
Jason