When a direct report is underperforming, being told as much may put them on the defensive. That’s why you should consider asking the person to evaluate their recent work. Doing so will open up the conversation and help you understand whether their view aligns with yours. Ask the employee what their key metrics are and whether they’re reaching them. If you two are in agreement, you can move on to discussing solutions. If not, explain what you’ve been seeing, citing specific examples of when the employee has fallen short. But be sure to listen to what the person says — you may discover a project is more involved than you realized, for example. Then work together to craft a plan for improvement. Ask the employee how they will address the issues you’ve identified. Agree on goals, a timeline for reaching them, and how often you’ll check in on their progress.
Source “How to Talk to an Employee Who Isn’t Meeting Their Goals,” by Sabina Nawaz