Defense.
If they can play consistent, decent defense, they'll have a shot at being a really good team. It appears they've got plenty of firepower offensively. The question is can they slow down the opposition.
Several takeaways from the first few games:
1. This team has a lot of individual talent, but there are so many new pieces, that they've got a long ways to go before they really mesh as a team.
2. If they don't really exert themselves on defense, even mediocre teams can stay with them.
3. When they play tough defense, it sparks the offense, and they'll be able to go on impressive runs.
Bottom line: If they play tough defense, this could be a surprisingly good team. If they don't, this team will be mediocre.