Stamina just means that your player can go longer n a game and still be effective, however on good teams you will usually have an 8-9 man rotation so your player shouldn't be playing 48 minutes which means as long as your players stamina isn't awful or below they are usually fine. Game shape is the thing that will give you that big advantage. You're doing a great job with your teams game shape though so thats good. As for training I would stop doing team training and start training your younger players (Houle) because they are the future of your team and since you have a 7 foot guard right now that means that Houle could turn into a really good SF or PF if he is trained correctly. I would focus all your training on him until the draft.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs