Yeah, Sega shows how to do it with the FM series. The Eastside Hockey games were great in that regard, too. And since you've mentioned more dynamic associations...another thing I've noticed is that it seems like generated player variety has decreased over the years.
I remember that 2k11 had more different types of players available. Some guards were pure shooters without much dunking ability, others could slash but were useless on the perimeter. In 2k13, it's all the same. Good guards have dunking/layup at least >85 in the beginning and become rated around 90 in every shooting category later on. And since sig skills are awarded when reaching fixed rating cutoffs, you'll see dozens of completely overpowered all around GOAT candidates for no reason. Just a very generic experience.
And potential is a good topic to bring up...I haven't played PES for a few years, but they had different types of developing presets with a few different timespans of players hitting their primes and so on. You know, stuff like players making huge jumps for a few years, then maybe regressing quickly while others improve rather slowly before making a surprising leap later on. Would be great to have that kind of model incorporated into 2k14 if there's still some time left after including Lebron's hand picked soundtrack suggestions...
Other things are mainly aesthetics, but give the impression of devs not giving a f*ck. Do all talented perimeter prospects need to have the Air Jordan package? Teams will sometimes have half a dozen players finishing like MJ with default rookie classes, quite often some white 6'0 PGs.
The same is true for jumpshot animations.
Would it be that hard to limit unathletic big men to getting assigned random set shots mainly? Maybe depending on shot ability and vertical? Right now, you'll see 7'2 centers having hangtime jumpshots like Dominique or Nate Robinson. Some 5'9 PGs on the other hand will jack up 3s with some useless Kevin Duckworth set shot...
Also, besides the generic all around megastar prospects, solid role players excelling at a few skills are pretty much non existent. Not much variety at all.
Association could be a great mode. But they should finally start to work on easy to fix issues which could go a long way improving the whole experience in a big way. If Sega can do it with some dry text based soccer manager, 2k with a multi million dollar budget and more than a decade of experience with assoc can't?