[Will Beh]

Hey! Elements in 26 will be similar to 25 and include;
player personality, coaching staff, age, morale, and a few much more minor ones. New to 26 is that if a player gets injured while in the lab, it'll slow down his day to day progress massively.
For the coaching staff I believe it's only the ones from the MLB that will be working at the facility, although different coaches are needed for different programs. I think the development budget affects the lab in a secondary way, in that it partly improves how well the coaches can work.
*Edit* And of course I forgot to mention, the programs difficulties themselves will define what's a success and what's not. In 26 with the new lab, it'll be much clearer what those cutoffs are