This is a particular good question from last year that I thought I would add:
Q. Assume that, pursuant to 11(b)(3), one specifically identified a factual allegation as lacking evidentiary support but likely to have such support after a reasonable opportunity for further investigation or discovery. Wouldn't that get you in trouble with TwIqbal?
A. I love this question, because it shows how Twiqbal (despite itself being an interpretation of 8(a)) is in tension with the Federal Rules. I agree that there is a problem under Twiqbal with a conclusory allegation of X (e.g. an agreement) even if the P has "proto-evidence" that would allow him to reasonably believe that evidence of X is likely to arise in discovery. An example is Sierocinski, where the fact that the cap blew up is (I think) proto-evidence - making it reasonable to think that evidence of negligence is likely to arise during discovery. The fact that Sierocinski (or his lawyer) satisfied R 11 in this way may not mean he has enough to satisfy Twiqbal concerning the allegation of negligence. That shows something is going wrong with Twiqbal.