My 2 cents:
I think that the GE tries to get a match before deciding what it's gonna be.
For example, JS gets divided with OD and the result produces the odds. Same goes with IS/ID etc. I think that SB firstly divides DR, before everything else. IRL games most shot blocks come from big guys when a small guy tries to drive and lay up.
Let's take a C with 10 SB, which is good. When this number divides a DR of let's say 16 the result is 1.6. Generally, I find that results between 1.1 - 1.4 are good odds for something to happen (a JS vs. OD or an IS vs. ID). 1.6 is a great number for the player that drives to be succesful.
In big division DR is generally better that SB. Way better to be precise, that's why players with good SB skills do not get that many blocks in a game.
Everything on this post is based on assumptions and there's not any proof.