Vanity metrics lose renewals
Most agency reports open with follower growth. It is the easiest number to pull and the easiest number for a client to dismiss, because it never maps to revenue. When a CFO asks what the retainer bought, a follower chart is not an answer.
The fix is not more charts. It is fewer, better ones: reach that is actually earned, engagement normalised by that reach, and the velocity at which an audience is compounding.
The three numbers that hold up
Reach tells you how far the work travelled. Engagement rate tells you whether it landed once it got there. Follower velocity tells you whether the account is accelerating or coasting on old momentum.
Track all three per content bucket rather than per post. A single post is noise; a bucket of twenty posts over a quarter is a signal you can act on and defend in a meeting.
Make the drill-down optional
A good report answers the question in the first five seconds and holds the evidence one click away. Lead with the number, keep the post-level table underneath it, and never make a client hunt through a spreadsheet to understand a headline.