I know I've written a lot here today. But here's one last thought.
I have been tasting my Oatquake 2 Oatmeal Stout the past few days. It is bottled and almost fully carbed and ready to go. Tonight I put it head-to-head with Sammy Smith's Oatmeal Stout. And I understand the problem I've got.
But first, to explain mine. The smell is roasty and dark. The appearance is black and opaque, with a sort of small head (it is still conditioning) that pretty quickly dissipates. The taste is bitter and roasty. Bitterness comes from hops, which are strong, and also from malts, which are dark. It doesn't really have that rich smooth feeling I was expecting the oats to give me, and that I had last time I used a similar recipe to this. The mouthfeel is a bit watery but sharp, combined with a prickly hops sensation. Overall it has a pretty low body, perhaps less than the pilsners I've been drinking lately.
Sammy's is so much richer smelling and fuller in the mouth. The basic flavor is pretty much the same, and the hops are pretty close. The problem is that I mashed my Oatmeal stout at too low a temperature. Until now, I've been confusing low mash temp with high efficiency. I can still get a good high efficiency mash at a higher temp, it's just that I might not hit a low FG with a higher mash temp. Which in this case would have been better. Mine is just too watery in the mouthfeel department. It has a mild body to say the least. I guess that's what happens when you finish at 1.015 on a stout. Well live and learn. I guess that's why the first Oatquake, which finished at 1.028 (for a whopping 1.8% ABV) was so tasty.
So this one is overattenuated. Normally you talk about beers being underattenuated. That normally means there are too many residual sugars and the resultant beer is too sweet. Well mine had the opposite problem. I made too many fermentable sugars, and didn't leave enough residuals there to make a substantial body that a stout needs.