From the TR blog:
What is FTP?
Functional Threshold Power is — quite simply — a measure of fitness.
I guess cycling “fitness” could be comprised of components such as cardiorespiratory endurance, strength, and power.
But here I am with 4 months of zero cardio, strength, or power training (aka fitness) and yet my FTP reads in the mid-200’s. In the 'How Fast Are TR Users" thread, this puts me barely on the right side of the bell curve: The Bell curve of cylists - how fast are the average TR users? - #203 by Nate_Pearson
But…if I did a race this weekend I would finish dead last. Got me thinking that there has to be other factors besides “fitness” going into what makes FTP. Any guesses – or actual facts – as to what those other components might be? 
Thanks for putting up with me! 