The best way to give critical feedback is to deliver it directly and dispassionately. Plainly say what you perceive the issue to be, what made you feel that way, and how you’d like to work together to resolve the concern. Both number three (I’m concerned about the quality of work that I’ve been seeing from you recently) and four (Your last few deliverables weren’t comprehensive enough to hit the mark) accomplish that, although number four gets a slight edge because it’s more specific in describing the concern.
