I'm still a little confused about the missions though. To get the points, do you have to have the players in your lineup or just on your roster?
Can I stack my bench full of 6'4 players and not have to use them?
No, you need to use them. A player has to play 1 full inning for it to count towards a mission. The more players you play that meet the criteria, the faster you progress.
You don't get tickets for every single player that meets the captain's mission criteria, you earn progress toward a 25 ticket reward for each player that meets the captain's mission criteria. If you look in the upper right, you will see something like 55/100. That is the progress you have made toward the 25 ticket reward.
So for example, if you have 10 players in your lineup with a jersey number over 40, Jacob deGrom selected as your captain, and play 3 Diamond Dynasty games, that progress circle thing will say 30/100. Play 7 more DD games and you will have reached 100/100 progress and will automatically receive 25 tickets. The counter will reset to zero and you can start the mission over to get another 25 tickets. The mission doesn't change once you've completed it
You can tell which players qualify for the captain's mission by looking at the player card and looking for the small "C's" on their player card. Using the previous example again, you will want to select players that have the 2nd "C" filled in, that is for deGrom. Donaldson is the 1st C, Altuve is the 3rd C, Rizzo is the 4th C, Hosmer is the 5th C, and Ortiz is the 6th C. A lot of the players will have more than one C filled in, so they qualify for multiple captain's missions.
Also, they made it unnecessarily difficult, in my opinion, to redeem card packs that you may have received for free. Press the touchpad, go to Show Shop, and select Purchase or Redeem. If you have any free packs, select them from here so they download, then go to Collect, then Packs to open the packs you may have just download for free.
Another thing, and this is just my opinion and preference, you can play how you want, but I don't sell any cards unless it is a duplicate. There are additional, non-captain missions to collect 25 players from each team, X number of stadium cards, and X number of equipment cards, so hang onto your cards to earn extra XP and stubs in the future.
One last thing, and again, this is just the way I play, but I don't use stubs to buy card packs right away. Initially as you're building your team to be competitive, I think the cards you get out of the packs are generally not worth what it costs to buy a pack. So use your stubs to buy player cards from the marketplace. You can pick exactly who you want and get a better value. You can be frugal and field a better Diamond Dynasty team for less stubs than a few packs of cards. A pack of cards that will inevitably contain duplicate cards that you already have, and a bunch of low rated players. Check if you have any free packs first though.
I understand how it works, but this here, this here is masterful work sir. People like yourself help make this community great. Awesome job.