I think there are three questions we need to answer.
1. Is this a block? Yes, it is.
2. Is it from outside the opponent's field of vision? Yes, it is.
3. Is it an open field block? I don't think so, but this is something we will be needing guidance on.
Kalle has hit the biggest nail head for this play, i.e., is it "open field?" No one has received a lot of guidance on this, yet. The "open field" component of the rule is clearly intended, for example, to allow an offensive tackle to take a couple of steps and blind-side an opponent in the general vicinity of the neutral zone. We get that. But this play is the quintessential example of the real gray area in this rule. The block isn't well behind or well beyond the NZ; rather, is it in the general area of the neutral zone extended to the sideline. But, the blocker is able to draw a bead on the unsuspecting opponent from a significant distance, and, with that distance, is able to attain enough speed to give him a huge advantage in momentum as he contacts the opponent. Put this action anywhere else on the field, and it would clearly qualify as "open field" (IMHO). Combine that with element of surprise and the inability of the opponent to prepare himself for the contact, or take evasive action, you have the resulting "big hit" that has the potential to cause direct injury. Not just momentary discomfort - but actual physical injury. And that is what the rules makers at all levels are attempting to mitigate.
We may get direction from NCAA folks that differs - or confirms - this conclusion (with rationale). But, we just don't have that, yet.
In today's political and legal environment, governing organizations are having to take pro-active steps to reduce their exposure to legal challenges related to what some folks may see as preventable injuries, whether immediately serious (or catastrophic), or long-term pathological conditions. That is what is driving these rule changes. Rightly or wrongly, we, as officials are being asked to play a part in changing the culture of football, to move away from the highlight reel "big hit" made on players that can't defend themselves. This is a huge, and very emotionally charged, change that everyone are being asked to embrace. Obviously, players and coaches are resistant to such a major behavioral change, and are struggling to accept it. I suppose it shouldn't be a surprise, but many officials are, likewise, struggling to adjust to this change, as well. Personally, I don't see this "going back to the way it was." We need to get on board and help make this a positive change. We shouldn't be afraid to make these calls (BSB and TGT, in particular), as unpopular as they may be with players, coaches, and fans. As I see it, it is already working. We already see players making wrap-up tackles in many cases that, in the past, they would have just blasted the ball carrier or receiver.
Let's work together for the good of the game. If we don't, we could see something happen that no one should ever want, and that is governmental intervention. That will be the death of the game as we know it.
Robert