USC's disastrous road trip to Boston to play Steve Addazio's Eagles was a perfect illustration of what's possible against an offense that's loaded with experienced linemen, hard-nosed blockers at tight end or fullback, and just a few guys who can make a play with the ball in their hands.

Coming off a bloodbath of a game with Stanford and missing star middle linebacker Hayes Pullard for the first half due to targeting, the Trojans were set up for a letdown. The Eagles obliged with a game in which they ran for 452 yards at 8.2 yards per clip.

USC was able to bring only 55 scholarship athletes to Boston for this game, and they took a licking that revealed the distance yet to be traveled for Steve Sarkisian to find a championship-contending roster. Between the lack of depth, the road environment, and the struggles of Michael Hutchings to provide the same heady play at middle linebacker as Pullard, the Trojans were simply not prepared.

For their own part, the Eagles mixed up a diverse game plan with a lot of different components, including a largely ineffectual passing game. Their ability to bring a diverse run game with zone, power, sweeps, and some pin-and-pull action, all complemented with QB options and misdirection, tested the Trojans' mental capacities early on.

Late in the game, USC's defenders were stretched to the breaking point and began trying to play football's version of hero ball, which of course set them up for the long runs by quarterback Tyler Murphy and that iced the game.

Having an offensive line entirely composed of fifth-year seniors, two great blockers at tight end, and the athletic tandem of Murphy and receiver Sherman Alston (four carries, 55 yards) allowed the Eagles to be more multiple in their run game. That forced the Trojans to think about myriad possibilities on every snap, not just the two running backs who each hit 89 yards.

But you could see the Eagles wear down USC's discipline and will with one play in particular, applied heavily over the course of the game: the zone read with a lead arc block by a tight end.

The common way this play is run is with the QB choosing to handoff or keep the ball. If he keeps, he's attacking the edge based on a read of an unblocked defensive end, with a lead blocker for him on the edge. The Eagles ran it just a little bit differently:

To begin with, they'd frequently run it from a Stanford-esque set with six offensive linemen, two tight ends, and a fullback in the backfield with Murphy and the running back.

Despite this being an obvious run play all the way, USC still struggles to line up in a sound formation. It's facing a double team on strong safety Su'a Cravens coming from two tight ends, while stud outside linebacker J.R. Tavai has to play a block by an offensive lineman.

And that's not even the most pressing stress point. The wrinkle here is that the read-side offensive tackle allows the defensive end upfield for Murphy to read, while the outside linebacker is handled in space by the arcing fullback. This effectively prevented the weakside linebacker from applying any pursuit, as he'd find his path cut off by an advancing offensive tackle.

If the DE looked to cut off Murphy and force him to give the ball, it would be all too easy for the running back to find an easy five yards or so behind the wall of human flesh in Eagle uniforms.

The play of the cornerbacks and free safety trying to read the play and then tackle Murphy in the open field was frankly humorous, as the Florida transfer quarterback regularly clowned them in space. Guess what happens when a defense doesn't have great answers for a play that allows such an athlete to get out in space?

That athlete can put up numbers like 13 carries for 191 yards.

In this second example, the Trojans on the weakside might be mistaken into believing they are safe, since the fullback is on the other side of the formation. But then a receiver motions across and takes out the previously unblocked outside linebacker, while Murphy relies on his fantastic change of direction to cut upfield.

The play of the USC secondary is again weak. While the corners and free safety may be pass-first players by alignment, they need to fill the alley much faster than that if they want to avoid getting embarrassed in the open field like this.

The beating continued.

In this instance, the DE does all he can to avoid to create indecision for Murphy, but the Eagle QB knows there's treasure around the edge if he just keeps it. The outside linebacker tries to take away the easy lane upfield and spill Murphy outside to the secondary's pursuit, but the corner has taken some false steps inside and only arrives just in time to get humiliated again by Murphy.

Late in the game, the Trojan offense still had USC in position to come back and win the game. Then Addazio and the Eagles rolled out their greatest hit for one more encore.

This time, they lined up in a double tight end set and motioned the back from a pistol alignment to a shotgun set. This action had preceded a few pin-and-pull runs earlier in the game, which had punished the Trojans for overeager play on the edge. This time, they used that pre-snap motion only to run zone read again.

Both the end and outside linebacker attack the mesh point, with the apparent intention to keep the ball in the hands of the running back and away from the edge. Unfortunately, these desperate Trojans are totally fooled by Murphy's pull, and both fall over themselves trying to stop the back.

Murphy goes for the edge once more. There is zero secondary help available to stop him, and with four minutes left, that's the ball game.

Despite getting repeatedly burned by not having enough pursuit in the defensive backfield to account for Murphy darting past unblocked defenders, the Trojan defensive staff has put all 11 defenders within five yards of the line of scrimmage.

Also problematic in USC's late response is that the weakside linebacker and strong safety both overpursue the play and allow a massive cutback lane for Murphy to exploit.

Boston College ran the ball 54 times, but an enormous chunk of those 452 yards came as a simple result of the Trojans being unprepared and eventually worn down by the Eagles' usage of this wrinkle on the zone read play.

It's difficult to play defense in this era. The Trojans have to have defensive plans they can execute against the Pac-12 gauntlet, including potentially Oregon in a conference championship game, which means finding answers for spread offenses.

Boston College hit them with varying looks featuring massive personnel, clearing paths for two of the fastest players on the field in Murphy and Alston. While Stanford applies a similar bruising approach, they don't employ option or field athletes like Murphy.

The Trojans would have been well served by having a big package that would have spared Cravens the responsibility of trying to beat double teams by larger opponents. And they would have been served by having a more prepared middle linebacker in the first half, but it's hard to do either with a limited roster.

The lesson, as always: if you don't have 11 men on the field who are ready to think quickly, move in coordination to take away running angles, and tackle, you are going to get burned.