Tinman, hope all is well.
Generally I agree that a runner should be trained to physiological strengths, but Ritz is an exception. He's actually in quite a tough spot.
Without a serious attempt to bring down his 1500/3000, his track 5000 and 10000 wont be budging much. He is already in point of fact,a superior 5000 runner to Teg. He loses on the speed side, just as Teg loses to Lagat on the speed side. This is not strictly a question of conditioning.
On the other hand if Ritz trains more traditionally, pushing his miles too high, he suffers on both sides. This is the big mistake Brad made, but they wisely adjusted by bringing him to sea level and cutting back the volume. And Ritz ran well off these changes. Still I think he could pull his miles even lower, down somewhere in the 85/week range, similar to Kibet, with even higher quality and run then he'll run his 205-206.
At this point the best bet is to point for the half marathon and the 59 range.
One of the downsides of this modern running scene is the vast money in the marathon. It is ironic that 20 miles with the lead at London would be worth more than the 209.
Now I have to laugh a bit when they say Ritz should get into a training group. An American who can talk at 450/mi is sort of in a no man's land. But thats Okay. Piling up more 630 miles will get him nowhere. He needs to hammer on his own anyway.