I was so afraid of this news. I actually mentioned this fear on another thread (related to Jager, which thread seems to have vanished). I guess that Derrick doesn't want to listen to me. :)
In my mind, he will get destroyed in the marathon prep and in the marathon itself. Not only will he not do well at the marathon distance, but it will also spell stagnation/regression for him over 5,000m and 10,000m... Oh well... I would have loved to see him progress some more at 10,000m...
Hope I'm wrong, but I doubt that I am. We have seen this so many times...