I'm lost a bit on what you are saying here. Are you saying that the various haplogroups have a set of STR alleles (values) that tend to revolve around the modal and are biologically pulled/held at or near the modals? Please clarify.
I said this many years ago. I was saying this when I was banned from “dna-forums” in replying to Ken Nordtvedt: it was the end of 2008. We see that in R1b1b2 and subclades, for instance DYS426, a very slow mutating marker, has mutated many times from R1b1 to the most recent subclades. How is it possible that it has mutated many times and other markers, fast mutating ones, are always the same? Because I think that markers mutate above all around the modal and sometimes they go for the tangent, and we have the “outliers”. Any clade is born with some values at a marker and these values are by chance, then tend to be around the modal and only sometimes different from it, if the marker is fast mutating or if, by chance, has a mutation for the tangent and not around the modal. Then every clade is a modal of itself. We don’t know how many mutations a marker has had if is the same of a previous modal, but if R1b1* has DYS426=12, if R1b1b2* has 11, if R1b1b2a has 12, if R-L51* has 13, if R1b1b2a1b has 12 etc, probably it isn’t reliable that other markers, most mutating of this, are always the same.
I wrote this many times also to Klyosov, who is a great chemist, and was snubbing a little me, but now is a “desaparecido”.