I was just going to ask the same question.
It makes you wonder if these ASIC producers actually aren't just mining with the hardware and claiming they're designing and assembling then once the difficulty heads north they dump the hardware and on to the next one. Tinfoil... I know.

It's just odd that the difficulty seems to trend perfectly with the availability of new ASIC miners.
I appreciate that increase in TH/s available to the bitcoin network should shave a corresponding increase in difficulty but difficulty seems to be the leading indicator here. Have I got it all wrong? CAn any one provide some insights on how difficulty works and why ASIC producers can't seem to have devices available in time to provide good ROI for a given difficulty level.