In my experience most "small pools suffering DDOS" are incorrectly configured.
Mining (all those getworks and stuff) can look a lot like a DDOS, one startup pool even had their host block them as they were getting "ddosed" they weren't they were just trying to load test...
The other thing that can be a problem is botnets, as far as I am aware most pools discourage them, do it wrong and anger one they can turn and DDOS...
apart from that conspiracy theory it up guys - you are doing great, I'm laughing
Probably it's the Martians trying to gain financial foothold here for world domination!
On a more serious note, I've kind of remembered that most DDOS's happen before a difficulty change - so my theory about difficulty decrease would be kind of correct.