ESPN has a really cool set of articles about Jordy Nelson's propensity for making the acrobatic back should catch. I would recommend both of them to everybody here (and you should read both together - they make more sense that way), if not only for the fact that it has become a staple route in the arsenal of teams with gifted QBs and athletic WRs. The first article is a traditional article and is presented as such. The second article is a neat graphic representation of the catch overlaid with quotations from Nelson in which he describes the process of running the route, positioning his body, and making the catch. This is the way cooler of the two, and I would definitely recommend checking it out.
I described the catch as a "staple route." Nelson might disagree, however. He might say, based upon his quotations in the more traditional article, that it's not really a route per se (in actuality, he claims that it's not a play). Nelson describes it as a reaction, saying that he runs a traditional go route, hoping to either beat the receiver for a big game (which would be a traditional go route), to engage in a jump-ball battle with the receiver (something we've seen the 49ers do a few times now), or to react to a back shoulder throw. What happens is, essentially, up to Aaron Rodgers, with whom Nelson has developed a sufficiently strong enough chemistry to make this reactive type of play a possibility. Because timing and reaction are so important, chemistry becomes a key factor.
This got me thinking about how the 49ers use the back shoulder fade. It's happened before. Colin Kaepernick does try it on occasion, but pretty rarely. And, it's not nearly as efficient as when Rodgers and Nelson do it. I think there are two reasons why it hasn't been as good yet, and both reasons lead me to think it might be better in the future.
First, the pass is usually a touch pass. Occasionally Rodgers will have to rifle it in quickly, but generally you want to get some air under the ball so that it goes over anybody dropping back into the flat, so that the receiver can go up and get the ball, and so that the receiver has time to come down with the catch. I will confess that I don't watch every Packers game, so my impression of how often the pass requires touch rather than speed might be skewed. If anybody has better information than I, please correct me! But, I digress. Since it's a touch throw, it hasn't been to Colin's advantage thus far to us it. Yet, this year, we've seen him really develop a lot, especially in respect to putting touch on the ball when he really needs to. I think that as he becomes more and more comfortable with throwing touch passes, the route tree will expand. Or, rather, what Colin can do with the route tree will expand.
This leads to my other point: I'm not sure how well Jim Harbaugh and Greg Roman would be at introducing new reads into their routes already. Maybe I'm wrong and these reads already exist; I can't know without the playbook. But, if Harbaugh and Roman have a weakness, it's the fact that they tend to favor powerful yet simple plays in contrast to nuanced and intricate plays. I'm not the first person to make this observation. Heck, I'm not even close to the first person to make this observation on this website. But, I do think it's true. The back shoulder pass might not be the Harbaugh-Roman style. Now, this year, we've seen them open up the playbook more than ever before. So, I do believe that as Colin progresses, so too will the playbook. It would be stupid to assume otherwise. But, when it comes to the 49ers offense, who knows what we will see.