In my opinion, the play is made because Desmond Clark handles Justin Tuck. Granted, he is on the weakside this play, but Tuck has the ability to run down Forte.
The strongside guard, on this play Frank Omiyale, does not get to the MLB and make a running lane if Tuck scrapes down the line looking for a tackle.
What took it into the end zone, however, is Forte's ability to find the hole and simply beat everyone on the field to the end zone. Once he hits his gear, it's enough to leave even DBs in the dust, as we saw on this play.
It doesn't matter how it's drawn up if your guy can't beat their guy.
This is how it unfolded:
TE1 Desmond Clark engages LE Justin Tuck, while RT Chris Williams cuts the inside man, NT Jay Alford.
RG Roberto Garza goes into the second level of the defense and gets probably a pinkie too much of SLB Clint Sintim, who gets to Forte's lane a second late. Garza whiffs about 89 percent on this play.
C Olin Kreutz is driven into the backfield by Barry Cofield, who is too involved and boxed out to make a play.
The "glamour" of the line comes from the LG Omiyale who gets to the second level and simply deactivates MLB Chase Blackburn, causing the huge lane in the middle of the field.
LT Orlando Pace pulls outside of TE2 Greg Olsen, slamming into the awaiting WLB Michael Boley.
Olsen, meanwhile, gets involved enough with RE Osi Umenyiora to allow Forte to run right by them both.
It should be noted that while Umenyiora, Cofield, and even Boley all had legitimate chances at the ball, given their position, none of them really did anything horrible to blow the play.
In the cases of Umenyiora and Boley, both tried to turn the ball inside, as they were coached to do—too bad that's where the hole was.
In Cofield's case, its as simple as being turned the wrong way. Had he gotten an arm free, this probably wouldn't have been a TD.