As others mentioned -- trust and commitment to follow-through on agreed-upon responsibilities. Truly working together and ensuring each other is always playing at their best. Comfortable calling out errors if they occur, validating results, and suggesting improvements. Keep the ego in check -- no matter how good we are -- when working as a team, you depend on others and vice-versa.

Maybe the words I'm looking for other than trust are knowing when to balance selfishness and selflessness. Self-control? Yes. Hopefully these would have been worked out by the time people play as a team. Stress & money can make folks do weird things. Just my $.02.