Mercado Envíos same-day on-time delivery in São Paulo fell from 92% to 81% in two weeks. How would you find the root cause?

Introduction

An 11-point drop in same-day on-time delivery in São Paulo over two weeks is serious. Same-day ("chega hoje") is one of Mercado Livre's sharpest weapons against Shopee, Temu and Amazon in Brazil, and São Paulo is its densest, most important metro. Buyers who were promised delivery today and got it tomorrow open claims, leave bad reviews and may stop paying for Meli+. Because the fall is fast rather than gradual, I'd expect a specific trigger: an operational change, a capacity shock, a data or promise-logic bug, or an external event. I'll narrow it down systematically before proposing fixes.

Step 1

Clarifying Questions (3 minutes)

• How exactly is "on-time" defined? Delivered by the end of the promised window on the same day, measured by driver scan?

Why it matters: A change to the definition or to scan logic could create a fake drop. Expected answer: Delivered by 23:59 on the promised day, based on the driver's delivery scan. Impact on approach: If definition is stable, the drop is real.

• Is the drop across all of Greater São Paulo or concentrated in certain zones, such as the ABC region, Guarulhos or the zona leste?

Why it matters: A localised drop points to a specific hub or route issue. Expected answer: Worse in some zones, but visible broadly. Impact on approach: I'd split by cross-dock and last-mile service centre.

• Has same-day volume changed, for example a campaign, a lower free-shipping threshold, or a new cut-off time?

Why it matters: Demand growth beyond capacity is the classic cause of late delivery. Expected answer: Volume up around 18% after a promo and a later order cut-off introduced three weeks ago. Impact on approach: Capacity and promise logic become top suspects.

• Did anything change in operations: a new sortation centre, a carrier partner swap, routing software release, or driver pay change?

Why it matters: Internal changes are the most common trigger for a sudden two-week shift. Expected answer: A new routing algorithm version was rolled out to part of the fleet. Impact on approach: Compare routes on old vs new versions.