Albuquerque's at 5200 ft and you can train up in the mountains as high as 10000 ft and while there is sometimes snow in the lower areas of the mountain, rarely is there any in the city, and the temperatures aren't very low at all, so it is a good winter training city at altitude. But if you grow up at altitude and train there for a long time, the altitude effects do not just go away when you train at sea level. I found significant improvements training in a semester in Abq, but then continued to pr at multiple distances in the years after I left, with the altitude effects seeming to persist for six months. And Hall has said over and over that at higher altitude at big bear or mammoth he is not able to train at the speeds necessary to go with the surges at marathon majors. This could well work very well this year before altitude effects decrease significantly for him. I hope that he has been training (or will train, for the Olympics) at much higher speeds with pace changes.