Hi SCurtis,
to ATP.
We've been wetter than normal here; have you? It looks like your soil has a pretty good amount of bark pieces...almost like potting soil. I'm wondering if your plants' root/crown areas are just a bit too wet at the moment because of this. Is the most stunted plant a bit lower than the rest? Maybe water is pooling beneath it.
BTW, all of my peppers in one area look like your littlest one; mine due to excessive stress, I think, during the time while we were away on vacation. I think they'll come out of it, but they sure are tiny now.