From the Feature List at the beginning of the stream:
"We've also made significant improvements to the existing systems that drive the mode:
-Player generation and progression
-Contract Logic
-Call ups/Send downs"
If
this really is noticeably improved, that alone makes the game worth the purchase for me. They mentioned things like Speed and Pitcher Velocity as things that guys have from the start, they don't increase over time from a low rating. This is really good to see that speed guys start out fast and pitchers with canon arms throw hard as prospects, rather than having to wait for those attributes to develop.
And in regards to progression, one of my biggest gripes was that even for A rated prospects, usually progression would happen in a way that you couldn't have a Mike Trout or Bryce Harper who were studs by the age of 22. Top prospects progressed way too slowly, or started with such a low initial rating that they wouldn't even make the big leagues until they were in their mid to late 20's. Maybe this has been improved too.