oddly enough 4.10 gave me more problems than anything else. 5.9 sale was annoying as well. Got through it 3 times with maybe 160 hold spent on boosts each time through.
Pretty sure no matter what you donate, it will only go up one level. So you only donate enough to go up a level and then donate again. Other than that, it's gloves that stop everyone from progressing.
I never do those ones. Just the hitting, pitching, and errors ones. Errors one you can always see a difference but who knows about the others. Also, I still don't know what penants actually do.
I got impatient and spent all my gold on that box. Pulled Cole, deGrom, and Walker. Also, Tdub I hate you. You beat me in bonus games and tournaments constantly haha (arug629).