Guess people have different takes on what they consider what a good player is.

For me the priority is:

1) Skillful. The basics makes you an average player, they are stepping above that threshold.
2) Adapt. They know the world doesn't resolve around them. Some situations you'll be pulling you out of your comfort zone and things might be different if the majority dictates it.
3) Good attitude. Know that this is a game and, in an instance, it's not a competition but cooperations between players.
4) Patience. Self-explanatory.
-Bonus: Be helpful. Not mandatory but always a plus. If people need/ask for help, be a buddy and give them some advice.
-Bonus II: They have a general knowledge about other people's roles/jobs. Helping them to synergize with them with their skillset.

A good player is an ideal, it's the one we all want in a duty. Individually and, if we can, we should always strive to become *that* player.