Video Review: Breaking Down San Francisco's Game-Winning Touchdown Against Lions

One great thing about being a fan of a good team is all of the bonus coverage you get from national outlets. This week was no exception, as the Lions played in one of the most intriguing games of the week. While much of the coverage focused on the post-game theatrics, there were also some very interesting articles breaking down plays in a similar fashion to what I do here. Over at Grantland, Chris Brown (not that one) broke down the "Wham" play, which was responsible for both of the 49ers long rushing plays. Many outlets have used Ted Ginn's punt return and the misplaced ball as a point of focus for the game.

However, out of all the coverage I've seen, I'm surprised to see that one of the lone stones left unturned was the actual play that won the game: Alex Smith's six-yard pass on fourth-and-goal. For all of the things that the Lions did wrong, if they would've just executed this play perfectly, they would've undoubtedly won the game. Let's take a look at the play and see what, if anything, the Lions could have done to win the game in this moment.

If you want to play along, the play begins at the 2:47 mark below.

Here's the layout of the play:

Bobby Carpenter, Louis Delmas and Chris Houston are labeled by their numbers because their actions are particularly important in this play. This play is designed to go to one of the two routes on the right. The routes are meant to make the men in coverage commit quickly and with the crossing routes, there is also the possibility of the two defenders getting in each other's way. Smith's other options are a fade route to the right, a curl to the tight end, or a short flip to the releasing running back.

The Lions linebackers are aligned to the strong side of the offense and are all playing a short zone, with the safety playing a deeper middle zone. The key to this play is the play of the linebackers, all of which are eyeing the quarterback to find hints as to where the pass is going.

The first thing that strikes me about this play is that Smith actually makes the incorrect read. Both Delmas and Houston see Smith looking at the underneath route and commit to that receiver. This leaves Michael Crabtree wide open heading to the end zone.

So, if two defenders jump the route where the ball is going, and Carpenter is in the zone where the ball is going, where does this play go wrong? Well, it appears to be on Carpenter; take a look:

Carpenter is reading Smith's (the "O" in this diagram) eyes. Unfortunately, he is reading where Smith is looking and not looking for who he is eyeing.  Carpenter starts drifting to the spot where Smith's eyes are locked, and this takes his momentum in the exact wrong direction. By the time he finds the receiver Smith is looking at, he is too far out of position to get anything more than a hand on him. Delmas did about as good of a job as one can expect on such a short, quick route and is unable to bring him down before hitting the goal line. If Carpenter reads the play correctly, he likely knocks the receiver back just short of the goal line.

Now, I'm not here to call out Carpenter or claim that if Justin Durant was healthy, the Lions would've won the game. Carpenter made a minor mistake that, if under any other circumstance, would have gone unnoticed by almost everyone. Unfortunately for Bobby, his mistake came on the biggest play of the game.