Jeff,
I find it interesting how much emphasis is placed on fitness...which contributes, but there is so much more to it.
I certainly don't have to tell you, but while length includes strength and flexibilty, it also includes technique, timing, eye to hand co-ordination, swing plane, shaft length, ball type, angle of attack, release points, etc.
P.S. Scott McCarron was one of the Tours long bombers back in the day too, when he was maybe 140 soaking wet...