Fast swimming in practice/unrested

Ande....having read your blog and a few others and seeing some of the times you've posted...as well as some of the mnd boggling in season/unrested swims going on this college and USS season I thought I'd bring up the topic of swimming fast in workout and in unrested meets. Having always been a VERY slow workout swimmer as well as a poor untapered swimmer I'm always amazed at how fast others can go in those situations. But I have noticed that those same swimmers don't necessarilly have big drops for meets they rest and shave for. So after seeing Michael Klueh from Texas go 4:11 unrested in the 500, my evil twin go 21.8/47.7 unrested (and at altitude), hearing you went 22.0 50 free and 2:00 in the 200 back at workout the question for everyone is what do you see in your own situations? Note; one thing that a few of us have noticed is that big old clydesadle types like me usually are the ones that drop the most from resting....little jackrabbits like JS swim fast all the time and don't seem to take as big of drops rested.