In the first image, you can get a sense of where each player was supposed to be, and there's Carpenter at the top. At least two players had collapsed down and weren't covering their lanes; and were too close to their teammate.
A few moments later, you can see what happened. Guys got bunched up, and particularly the guys in the dark circle are out of position - at least one of them is, anyway...if they had been covering their lanes, this might not have ended this way.
The fast receiver blew past a guy out of position and the bunches that were all blocked. And now its off to the races.
This was corrected in subsequent returns.
Incidentally I noticed that the "benched" Vontae and Sean Smith were both out on the coverage team. I have to assume that they haven't played special teams much and were among those out of position on the play...