More important than the solution is how you present and communicate that solution. Have you offered support and tools for them to close the gap between what's wrong and what needs to happen? Also, have you made things perfectly clear? Is your feedback unmistakable, and is the sol unmistakable? And if you're trying to fer out how to build up trust, revisit the episode on radical candor that talks about caring personally while challenging directly. Will link to it in the show notes.