US and Europeans are grinding altitude camps year round and are doing more threshold work. I think both Hocker/Jakob have been running since they were kids, I imagine this has helped them get ahead of the curve. Also, running in the US/NCAA/Euro circuit is better/more competitive than ever. We're so much deeper than ever before, there are like 25 dudes in the US that can run 3:32 or 13:10.
I'm not really sure what the history of training at altitude is in the US, but I imagine that if running becomes even remotely as technically advanced as cycling (fueling, training, altitude, recovery) it's over for athletes that are not getting the same support as the athletes in pro Nike/Adidas/etc. running groups (in the US/Europe)