The problem with advice like this is that, as a result of following it, you become a phony. The "don't go back to being buddy buddy" stuff is just odd. It's manipulative at worst and unnatural and uncomfortable at best.

My philosophy is this: If you're half competent at choosing your team and someone you lead isn't performing, it's probably your fault. So before you decide that "your employees have made a mistake," you should probably be clear on whether not you made a mistake first.

Are the expectations clear? I bet you they're not. Leading people means exhaustive communication, especially about details and success conditions. If you're not sharing this stuff, you're not providing useful leadership.

Have you communicated the stakes? If something is important, don't assume that everyone else knows that. What makes it important? Why should anyone else case?

Are you available to help? If you're not making time to check in and support as unexpected complexities of the task crop up, you're in for some nice surprises at the end.

When people fail to meet the needs and expectations of the task, are you direct about it or do you pretend everything is cool? Do you look for opportunities to teach about the failing, explain what was disappointing? Most importantly, do you point out how to do better next time?

When people do outstandingly well, do you recognize that?

The tl;dr of this: getting what you want from people is a combination of being proactive and communicating. Not micromanaging, not being a babysitter, not being a bully, not being a softie.

Be direct, don't expect anyone to read your mind, understand you're part of the process as a leader.

(All this collected from being led by extraordinary leaders, lazy ones, and outright terrible ones.)