The lasting memory of Sunday’s game against the Giants may be Terrance Williams’ inability to get out of bounds as time expired. However, the part of the game that Cowboys fans should be more concerned about is the performance of Dak Prescott.

The Mississippi State rookie made his debut after a much heralded preseason campaign. On the day, Prescott threw for 227 yards on 45 attempts with 25 completions. Prescott’s 5.04 yards per attempt and his 55% completion percentage are reasons enough for concern, but when you look at his performance more granularly, you see can see how some of his deficiencies had an effect on the offense as a whole.

Because of Prescott’s inability to push the ball down the field in an effective way and establish a vertical passing threat, the Giants were able to play with the advantage inside the defensive run area and hold the Dallas ground game to 101 yards and 3.4 yards per carry.

How Will Dak Prescott Affect the Cowboys Offense?

Prescott’s Day Through the Air

The passing chart above attempts to illustrate the distribution of Prescott’s pass attempts on Sunday to different zones of the field. For example, the bottom left rectangle shows the pass attempts Prescott had that were behind the line of scrimmage (BLOS) to 10 yards down field; on those throws he went 9-of-11.

The clear defect in Prescott’s performance comes from pass attempts that went longer than 20 yards in the air. He not only failed to complete a pass that traveled 20 yards or more, he also only attempted five passes of twenty yards or more on the day. However, the lack of attempts may have been a result of the general ineffectiveness on the attempts that did take place.

Out of his 43 attempts—total attempts minus the two spiked passes—28 of the passes were behind the line of scrimmage to 10 yards down field, which is suggestive of the Cowboys desire to give Prescott manageable throws and attempt to run the ball effectively as a general game plan. But in this case, as we’ll soon talk about, the former may have come at the expense of the latter as the two aims proved to be somewhat mutually exclusive against the Giants defense.

Take the play below as an example:

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The cowboys line up in a 3×2 formation, with the strength of the formation to the field.

The Giants line up with a single high safety and are in Cover-1 man.

The motion of Alfred Morris (which turns the formation into a 3×1 set) transitions Landon Collin’s man responsibility from Morris to the new #1 receiver on the outside, Jason Witten. Jonathan Casillas now has man responsibility against Alfred Morris.

A question that one might have about this play is why Prescott didn’t go with the underneath route to Jason Witten. Witten and Beasley run a mesh route over the middle, and Landon Collins is forced to work around Beasley and his defender, which leaves Witten wide open.

If the answer to that question is that the Cowboys wanted to take a shot into the end zone, that’s understandable. The issue then comes down to the placement of the pass. Dominique Rodgers-Cromartie is able to make a play on the ball because Prescott places it in front of Dez Bryant. The safety rotates to the boundary and takes himself out of the play, which leaves no help for Rodgers-Cromartie over the top. If you watch the video, you’ll notice that Bryant has to slow down around the time he gets into the end zone to adjust for the underthrown ball. A better placement of the ball out in front of Bryant may have allowed him to come down with the catch.

As the Cowboys passing attack was unable to come up with a downfield threat and was forced to stick with short and intermediate throws, the Giants played with a single high safety on 65% of snaps (excluding the snaps from the Cowboys’ last drive of the game when the threat of the run was gone), allowing them to leave an extra defender in the run game.

How the Pass Affected the Run

Despite the talent on the Cowboys’ offensive line and the addition of Ezekiel Elliot, the Dallas running game struggled to produce against crowded Giants defensive fronts.

Out of the Cowboys’ 30 runs on Sunday, 19 of those runs went for three yards or less, nine runs went for four to nine yards, and only two runs went for more than 10.

Think back to when you heard a commentator talk about how the defense rolled a strong safety down in the formation to get “eight men in the box.” The goal for the defense isn’t necessarily to get eight men in the box; the goal is to have one more defender in the box than the offense has blockers.

For our purposes, we’ll define the box as the rectangular area between the last defenders directly next to the offensive tackle/attached tight end on each side of the offensive formation (horizontal limit) and seven yards past the line of scrimmage (vertical limit).

Take the image below as an example. This is from a run late in the second quarter that resulted in a loss of two yards by the Cowboys:

The Giants are lined up with a single high safety and have eight men lined up inside the box, while the Cowboys only have seven blockers. This means one man will go unblocked. The Giants can line up with a single high safety and bring an extra defender into the box, because they aren’t afraid Prescott will beat them over the top.

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The Cowboys try to run a sweep with their center and tackle, but Olivier Vernon pushes back Jason Witten on his down block to collapse the running lane, and Devon Kennard does a great job setting the edge against Tyron Smith.

Damon Harrison sheds his block to make the tackle, but the fact that the Giants have one more defender than the Cowboys have blockers makes the margin for error very slim.

Out of the 30 runs the Cowboys had on offense, the Giants had more defenders than the Cowboys had blockers on 18 plays! Not surprisingly the Cowboys only averaged 2.8 yards per carry on these plays, while they averaged 4.8 yards per carry on runs where they had the same amount of blockers as the Giants had defenders in the box.

The extra defender clearly matters and the reason that the Giants were able to bring an extra defender into the rush area was because of the absence of a downfield passing game. If the Cowboys were able to push the ball downfield and challenge the seams, the Giants would have been forced to adjust their coverage.

The success of Dak Prescott and the Dallas offense (as long as Prescott is the quarterback) may ultimately come down to whether or not the Cowboys and Dak can establish some type of a vertical passing offense. Until that happens, expect teams to continue to line up with a single high safety and an extra man in run defense.