So Cal,

I think the question you ask about the improvement of 3YO's with age might be answered by a study I once did. I found that from Jan-April, the avrage 3YO stakes winner's figure is about 3 points slower than for older horses.
From May-Aug the difference is 2 points and from Sept-Dec it drops to 1.

I'm sure Jerry has a formula for expected improvement with maturity and hopefully he'll be kind enough to post it. I'd be curious to see how it compares with mine, which was done several years ago.

Bob