I have several AAA players that are nearing their big league opportunity but I want to maximize their development this year. Presuming the same amount of playing time in majors, do they develop more, less, or the same at either level?

All things equal, they would develop more at the major league level because they would theoretically have better coaching.

That said, I wouldn't make my team worse by playing someone at the ML level instead of someone else who is better, just to maximize their development.  If it's not making your team better by calling them up, then let them develop in AAA. 

The idea that players stop developing at the major league level, or that development slows down, is just a myth.

As long as they are playing full time at the MLB level, they will continue to develop just as well as they would in AAA.

I see a lot of questions in these forums, re-wording and overcomplicating "development."  Is there anything else to development OTHER than giving them better coaching and all the playing time they can handle?

Training and medical, to keep them healthy and to help them recover when they do suffer injuries.

Good point.  I took it for granted since I budget 20/20.

If a player is nearing his "BL opportunity", it's not likely that much development will take place either way. 

Posted by damag on 12/12/2014 11:11:00 AM (view original):
I see a lot of questions in these forums, re-wording and overcomplicating "development."  Is there anything else to development OTHER than giving them better coaching and all the playing time they can handle?

The players' guide also says that "age appropriateness for level of play" affects development. So I would think that if you sent an 18 or 19 year old to the majors, it might stall his development a bit. On the other hand, if you kept a 23 year old in AA, that's probably a bad idea too.

if you have a 23 year old who is still in AA, he probably belongs there

The average age of a AA player in real baseball is 23.8 years old. However, I'm assuming arcticlegend is referring to elite prospects, who would be on the fast-track to the bigs.
Personally, I I don't like to put anyone in AA who isn't at least 20 y/o yet. To me, that would fall into the category of too young for the level. I've also found that minor league filler guys are very likely to retire if they aren't at least in AA at rollover of the season in which they turn 25.

Also, for those curious... this is what I found for average ages at all minor league levels this year in real-life;
AAA = 28.2 (obviously higher, due to use as a parking lot for AAAA players, veterans, etc)
AA = 23.8
Hi-A = 22.4
A = 21.2
Lo-A = 20.9
Rookie = 19.4

The flaw with those numbers, in my opinion, is that HBD has a fairly regimented maturation process. I.E. a prospect drafted at 18 will reach his potential, for the most part, by age 21 or 22, thus making it worthless to keep him in the minors if he's a valuable prospect. 

As HBD goes, you know you control the guy for 10 seasons(3 min, 2 arb, 5 LT) if you don't do the horseshit "hold back 20 games when I could really use wins" strategy.    You also know position players start their physical decline in their early 30s.   With that in mind, having a valuable 24 y/o in AAA is sort of dumb.   Unless, of course, you only want to do 1 arb and/or hope he'll accept less than 5 years when LT contract time comes.