It's all down to what you're accustomed to. I drove for over a decade on r-compound tires. Between my old car, and Steve's STR car, I saw the difference something like this:
Street tires:
aaaa-bbbbbbb-cc
Hoosiers:
aaaaaaaaa-bbb-c
Where:
a = driving too tidy
b = "slithering," just the right amount of slip angle to be fast.
c = too much slip angle, about to go backwards or crash.
Speed increases from left to right, until you hit the "c" part.

It was damn difficult to keep my Hoosier-shod, stock class S2000 in the "b" part of my fancy diagram.

Similarly, it was hard for me to tell how much sliding around was fast in Steve's car. I'm not a fast learner anymore - I'm an old man now, and I'm set in my ways. I'd have needed an entire season in that very excellent STR car to figure all of that out. Wish I'd been able to do that.