This game is a really great "no money spent" experience compared to any other sports game out there, and it's great that there's so much content.
But, I haven't heard any good answer to the question - what's the point of all these rewards when we already have a full team of 99s? What are we supposed to do with all these cards? As a veteran of role playing games, I love grinding and "collecting em all," but it seems so obvious that we need places to use these cards that give the player a nice advantage for collecting them and using them.
I think SDS would say "we know this is a problem, but we just have to put out max 99 content around All Star game, because player base goes out the window at that time no matter what....so it's just all 99s from then...."
So, the obvious solution is - give us a serious mode where we can use the other cards! A mid-90s diamond is super useful on a theme team. You could have all sorts of fun themes - players from venezuela, players whose names end in a vowel, whatever!
Some of you may say that we can just create our own theme teams for fun, and we do....but it's not as fun when you're getting thrashed by "guy who plays his god squad 500 times per day in Ranked and doesn't care to do anything else" while you're playing with your cute Diamondbacks team.
It needs to be a real mode (both online and offline) with real rewards for the people who have a deep portfolio of players. If you don't have a deep portfolio, you get stuck with commons or bronzes in the mode. Team Affinity parts two and three are needed for offline grinding. These are simple fixes to avoid the obvious problem of "thanks for giving me another 99, but I already have four at that position!"