Open your product performance dashboard right now and you'll probably see a leaderboard: top SKUs by revenue, sorted high to low. Looks great. Tells you almost nothing.

A product can sit at the top of that list and still be bleeding money once you factor in the 22% off discount code it ran last month, the return rate quietly climbing, and the ad spend it took to get those sales in the first place. Revenue per SKU is a vanity number dressed up as an insight. Product performance KPIs are supposed to fix that, but most teams only track the one or two that are easiest to pull, not the ones that actually tell them whether a product is working.