I’ve used the term ‘Route Stem’ or ‘Stem’ several times through articles and podcasts last season while discussing the New York Giants. A route stem is the initial vertical element of a route before the break.
The term route stem branches off the commonly understood phrase ‘Route Tree.’ The simplest picture I found depicting this concept was in an article written by Matt St. Jean of Inside The Pylon - my former working space.
The stem is red. You may also hear pundits say the receiver ‘stemmed inside.’ That could mean a few things. Depending on the play and route, receivers initially release inside (or outside) to open the cornerback’s hips and create space for their subsequent move, or ‘branch.’
Isaiah Hodgins (18) ran a smooth pivot route to score against Washington in Week 13. This is a double move where Hodgins stems to the inside to illicit a reaction by the cornerback. Even though the inside move isn’t on the vertical stem, it’s referenced as a stem because it sets up the subsequent route, which is the pivot to the outside.
Receivers master their craft of manipulating defenders by disguising their intentions while running up their stem. This can include footwork, upper-body movement (head, shoulders, etc.), controlling release tempo, double moves, and various other ways to influence cornerbacks away from their leverage and responsibilities.
Football is a tight game, and the throwing windows are small. What seems like the most trivial of movements could be the difference between an incomplete pass and a touchdown. The best receivers in the NFL understand that fact.