The 49ers finished the sweep of the Rams this season last Sunday largely on the back of their defense, who intercepted quarterback Jared Goff twice, including one pick-six to open the second half, recorded two sacks, and forced two fumbles, which the defense both recovered. It was the most complete defensive performance in a season full of injuries and uncertainty surrounding the teams fate as they enter the final quarter of the season.

While the pick-six and interceptions are noteworthy plays, todays Anatomy of a Play series is going to focus on how the 49ers shut down the Rams favorite passing concept: the weakside choice route to Cooper Kupp.

The Rams favorite passing concept to Cooper Kupp this season is a simple choice route. The choice route gives the receiver a 3-way go with the option to sit in the zone at a depth of six yards or cut across the field or cut to the outside in the flat depending on whether the defense plays man coverage and what leverage they have on the receiver. The most important aspect for the quarterback is being in sync with the receiver and seeing the same coverage post-snap as the receiver.

For the Rams, the choice route on a passing concept called choice stucko is the preferred call to Kupp in high leverage situations on 2nd or 3rd and short. The Rams have called the play for several big plays this season.

Choice stucko is a passing concept where the choice route is primarily run from the slot or from the outside receiver in a stack formation.

The receiver to the same side runs a comeback if the choice is in the slot and runs a corner route if the choice is the outside stack receiver. The choice is the first read, with the corner/comeback being the second read. The other side has a stick china route from the tight end, or slot and a widen scout route as the alert with the option of converting that into a go route. The stick china is the third read in the progression.

Cooper Kupp has had two big plays running the choice route on this play from both the slot and the outside number one in the stack.

In both plays in the clips above, Kupp cuts to the inside off defenders with outside leverage. In the clip against the Eagles, the corner is playing off slightly as Kupp takes an outside track at the defenders outside shoulder, getting him to widen. He slow rolls his release and cuts inside, where Goff finds him for a gain of 24 yards. In the clips against the Giants, The Giants send a snake blitz (slot corner blitz), so the safety rolls over to cover Kupp. He takes away the outside as Kupp widens him, but Kupp cuts inside, catches the pass, and sprints to the end zone for the touchdown.

In week six, in their first meeting, the 49ers denied the Rams opportunities to run this route effectively, and the Rams offense suffered; as a result, being forced into unwanted third-and-long situations or punts.

In week 12, the Rams tried throw to Kupp twice on the choice route on choice stucko, and both times Goff was sacked by Kerry Hyder because he held onto the ball too long after coming off his initial read. It helped that no one was open too, but Goff has enough veteran presence to know that he shouldve thrown the ball away.

1st sack, 2nd quarter 1:43, 1st and 10 at LAR 20

The Rams are running choice stucko this time with Kupp in the slot. But the Rams designed this with a wrinkle. The tight end Gerald Everett (No. 81) is flexed out wide left, making this the strong side of the formation.

The 49ers are playing cover-1 with a low hole dropper to the strong linebacker Dre Greenlaw (No. 57), with Jimmie Ward (No. 20) in the slot covering Kupp. The Rams figure it might be easier to complete the choice route over the middle with Greenlaw rather than Warner as the hole dropper.

Ward follows Kupp on the motion across before the snap. As Goff drops back and looks for Kupp running the choice from the slot, Greenlaw flies to the route as the low hole defender.

Goff has nowhere to throw as Kupp cuts inside so he scans his other progressions and takes a sack from Kerry Hyder.

2nd sack, 4th quarter 9:38, 3rd and 4 at LAR 36

The play call is the same except this time Kupp is the number one receiver in the stack to the left running the choice underneath Van Jefferson on the corner route.

This time the 49ers send Warner to the weak side because the tight end is over to the opposite of the stack bunch. Theyre still playing cover-1 with Warner as the low hole dropper.

Verrett is in coverage over Kupp to the outside this time, with Ward covering the tight end to the opposite side. Goff drops back and looks for Kupp, but Warner sinks under the route and takes away Goffs primary read. Goff has nowhere to go and Hyder cleans up with his second sack of the game.

The 49ers swept the Rams again this season, and 4-0 over the last two seasons with Kyle Shanahan improving to 5-3 over his former colleague Sean McVay. This time, the win came on the back of a superior defensive performance by Robert Saleh.

Excerpt from:
Anatomy of a play: How the 49ers denied the Rams their favorite passing concept and generated sacks - Niners Nation