Sorry. Just saw this.
Cover 3 man and zone combo. Four man rush with stunt on the right side.
Goff has a seam route and a post route that takes advantage of Cover 3 zone.
Right before throw.
Once Goff recognizes Cover 3, he should've made the seam or the post route his primary. Gurley could've had a first down also. Actually, Kupp was open for the first too. Woods was open. Goff just threw it too late. He had heat from the stunt so maybe that affected his decision making.
But once he recognizes Cover 3, the seam route was there for a quick thow and a huge gain.