A question was raised about rushing a player to the ML level or not. That is a question that has been debated in several worlds that I am in. The answer is not exactly easy and depends on several factors. As some would say it ends up being about money well spent in the right places begets results. I will give you an example or two and you can discern from there.
Ben Fox - was called up at the tail end of last season. It was more out of need than anything else. I really didn't want to call him up last year except at roster expansion. He was close to his projections at any rate even then. Most players slow down in their rating increase after their first 3 full seasons by observation. I am not saying they quit gaining but the rate of increase slows. He will make a great Gold Glove 3B IMHO, maybe even this year. His hitting and defense will get a little better over time but I expect the increase to be slow because he is at the ML level. They tend to slow down more at the ML level than in the minors after the 3 full seasons and I am not exactly sure why. It could be the strain of playing at the ML level. But I still expect him to be fully maxed out on current projections by the time he is 26 and maybe exceed them.
Cyrus Neal - if you look at his ratings he was called up to the ML in season 2. Actually what happened is I took the team over about 15 games into the season and I had 10 position players on the ML roster and nothing in the minors that could even be considered a ML player. So he was put onto the ML roster due to a trade. If you notice he progressed well through season 4, think part of that was because it was a winning team in season 4. After that he has not progressed very fast and really has a little ways to go, more than Fox even.
Now that you can see the difference in that respect, I will give you some more information. When I took the team over, the budget was set to minimum which didn't help. That means it takes 3 seasons to get the training budget to max. Then I didn't put the training budget to max when I could have and that was a mistake. Corrected that this year, so I will hopefully benefit from the rewards next season.
As for ratings improvement there are several factors one must pay attention to in my opinionated view.
1. The first 3 full seasons will be the greatest increase to most players.
2. A good FI and decent coaching helps in the minors.
3. A maxed out training budget goes a long way.
4. A players patience and makeup also play a big factor.
5. Putting an Amateur draftee into a higher level other than rookie doesn't advance him any faster, that is an observation. As far as I can tell, the player will get 2 ratings bumps and a promotion bump and they will be the same no matter where he is at.
6. The placement of a blue chip IFA can be tough where age and timing could be the key.
7. Getting heavy playing time helps at any level. That means the field as well as ABs and innings for pitchers.
8. Not letting players get into heavy fatigue also helps.