Nice catch!
Edit:
Checked on my scrapper: evasion is solid for 21.8% DDR.
Checked on my brute: evasion is solid for 22.13% DDR.
Checked on my tank: evasion is bbbbbbbbROKEN, phasing in and out for 27.25% DDR with no change if enemies are around or not. I should note, however, that even with it gone, my tank sits at 94.51% instead of 95% so I doubt this was the cause of the OP's cascading defense failure. Edit2: Nevermind. From the screenshots, I can tell that he's not slotted up fully.