Don't Hold Feedback
It's a terrible feeling when you find out that your actions have been corrosive to the team and you've been unaware. It's one thing to know about your faults and do nothing about them, that's obstinance. But if you're doing a job incorrectly or poorly, under the assumption that you're doing well, a harsh correction will appear "out of the blue."
When you have employees or teammates that are missing the mark, and they seem unaware, tell them as soon as possible. Don't let it slide and see if they improve over time. That will cause frustration for you, and the rest of the team while the worker sits unaware. One day those negative emotions will come to a head and the person receiving them will be in shock.
Giving constructive criticism is hard. You don't want to hurt a person's feelings or have to tell someone they're not good at a thing, but it's necessary. Regular, constructive feedback will give the worker a clear objective and reduce the possibility of a "blow up" happening within the team.