The answer is very easy : the training methods have evolved very much WITH TOP AFRICAN ATHLETES (speaking about long distances), but at the same time have INVOLVED very much with European athletes.
When I have some course with European Coaches (for example in IAAF Academy), I see a lost of mentality about long and fast run, compared with 30 years ago.
In 2008 I was in Porto fof speaking with Portuguese coaches, and they said "We cant compete with African runners". I asked them "Which is the best seasonal time in 10000m this year ?" and they answered something better than 28'50". So, I asked "Do you know that not in Africa, but in this Country, 25 years ago you had two athletes running 27'12" (Mamede) and 27'17" (Lopes), ine oif them winning Olympic in Marathon after winning World Cross, that can almost give 2 laps to your best runners of today ?".
So, it's clear that in the European art of coaching there was an INVOLUTION, not an EVOLUTION.
Anders Garderud used long fast run (really, not so much, coming from 1'47" in 800m, and going to 13'17" in 5000m...) and for that reason, together his talent, he became Olympic Champion and WR holder running 8'08". Why now the other athletes are so far from him (apart the period of Mustapha Mohamed) ? Why the Italian are so far from Cova, Panetta, Antibo, Lambruschini ?
Because our society changed, and now is very difficult to recruit good talents for running. And, without good talents, top coaches are interested in some other sport, so the specific knowledge about training is going down. If you speak today with a young coach, he doesn't know anything about the history of athletics and of the evolution of methodology, so we lost all the experiences of the past.
But this doesn't mean that the experiences of the past can be considered the arrival point. For who knows the evolution of methodology, those experience are the base for developing new methodologies. Physiology now knows very much more than 40 years ago, but this knowledge became baggage of a small elite, because the general interest about running at professional level went down, not involving young people because there was no money around. Now many coaches survive writing program on line for amateurs, and the goals are completely different from that of top runners.
So, I repeat that the Lydiard phylosophy is still the base for developing the aerobic ability, BUT NOW PRACTICALLY IS WHAT MEDIUM LEVEL RUNNERS CAN DO, NOT TOP PROFESSIONAL ATHLETES.
I explained many times athletics today changed, and the athletes must find the best system for earning money reaching top results and, at the same time, trying to last. Now there are competitions during the all season, there are musts with the Companies about contracts, there are major marathons important like WCh, there is Diamond League already asking 7 competitions in the same event at top level, there are Championships every 2 years.
For that reason, TOP ATHLETES NEVER HAVE TO LOSE WHAT ALREADY THEY HAVE. It's not possible today to have a long period of preparation without ALL the elements of training (including speed and long fast run already in fundamental period). Of course, what can change is the PERCENTAGE we use for every type of training during different periods.
For too long time we had in training the FRIGHT to do something AGAINST the development of some quality. So, 50 years ago, many coaches supposed using speed during the base period could affect the aerobic system, exactly like many coaches of sprinters didn't accept 40' easy continuous run because could affect the speed.
This is a total stupidity. In training, THE ONLY THING CAN LOSE IS WHAT YOU DON'T DO.
And, looking at the current results, we don't think the new methodology can be so bad.