Last year I was shooting at an archaeological place and I dropped my 24 TS-E 24mm II.
Immediately I put my foot and decelerated its fall a lot. It landed at a wooden floor. It had its cap.
Nothing happened not even a scratch on the plastic areas
I still try to figure how on earth my 5D2's screen was damaged. Screens are inside and cannot in any way be harmed by a dropping lens (I hadn't put any finger inside).
Anyway I happened to have a Grid Screen which I hadn't used yet. So I replaced the screen and everything was as good as new