I think you are misunderstanding something, because the numbers in both places have always lined up for me, with the exception that the contract negotiation page will take into account the upcoming cost of signing draft picks if you're pre-draft, while the team page won't subtract it from the "available cap" stated. (although it does list on the team page the cost to sign draft picks as a separate line so you can do the math pretty easily there.)

IDK? It was at the camp stage when I grabbed the team. From here on out I am using the numbers accessed from the player card. They worked as they should and all the numbers line up now.