That's interesting. Can you elaborate further - specific correlations???

I just starting riding in December 2012 after many years of almost no physical activity and training hard (or at least in my mind I have) and have focused on training for NC mountain events so my main focus was power over a long period of time. It may be that if I'd train more to increase my FTP then I'd get side benefits of improving power over longer rides. I know I'd still need to include endurance rides in my training.

For my current level it may be just as simple as "ride more", but like Friel says you need to maximize the benefit obtained from all training rides.