Let me clarify, because I'm not really trying to argue that having a good season causes you to be better. I'm not saying that a superstar 91 OVR QB who passes for 4,000 + yards should automatically go to 99 OVR.
My main point is really about playing time and experience (which you seem to agree with)--a freshman who starts 12 games should have a bigger ratings bump in the offseason (particularly in something like AWR) than the RS freshman who didn't see the field all year. A guy who suffers a season-ending injury in week 2 should progress less in the following offseason than his backup who steps in and plays the remaining 10 games.
My second point is that, to some extent, success in a particular attribute during a season should influence offseason development. If my halfback has a catch rating of 58 and I really focus on developing his receiving skills during a season by having him catch 40 passes out of the backfield, his catch rating should increase appropriately to reflect that extra successful work. Players with low ratings in certain areas who have good stats in a season in those areas should have their abilities adjusted to more accurately reflect the successful season they just had.
I do like your ideas about potential and work ethic ratings. I think the most important thing is development influenced by playing time (because that's how real players get better), but I'd like to see those new ratings incorporated as well.