The Dallas Cowboys have taken offensive linemen in the first round of the NFL Draft three of the past four years. Now, their offense is as efficient as ever. Coincidence? I think not.

Back in 2011, the Dallas Cowboys were coming off of a season in which they finished 6-10. The defense had allowed more points than any other in the NFC, and they were begging for a competent running back. The team drafted tackle Tyron Smith ninth overall.

Two years later, things still weren't popping in Big 'D'. So, of course, they traded out of the 18th overall pick and selected center Travis Frederick at 31. Troll so hard.

Now, they would never do this for a third time, right? Especially with the most Jerry Jones selection ever in Johnny Manziel on the board, right? Wrong. Out pops lineman Zack Martin, severely lacking in swag and slammin' pre-game parties. Do they even want to win?

Well, here we are. The Cowboys are coming off of their first playoff appearance since 2009, and the offense was more efficient than it has been in well over a decade. All three of those first-round picks have been selected to the Pro Bowl this season.

But Johnny Football, doe.

Is this a coincidence that the Cowboys' success came after drafting three offensive linemen in the first round over the course of four years? Or is this common for teams that are seduced by the size? Because of this fun little thing called data, we can find out.

Method of Analysis

For purposes of evaluation, we'll be using numberFire's Net Expected Points (NEP). This is an efficiency metric that shows how a team performs relative to a league-average team. So, a team with a Passing NEP of 30.00 would be expected to be 30 points better than a team with an average passing offense, give or take a few expected points since passing is more efficient than rushing.

In this instance, we'll roll with each team's Adjusted Passing NEP per play and Adjusted Rushing NEP per play. These numbers are adjusted based on strength of schedule and scaled down to a per-play basis. For reference, the average Adjusted Passing NEP per play this year was 0.08, while the average Adjusted Rushing NEP per play was -0.01.

This study will include each of the 73 offensive linemen taken in the first round from 2001 to 2014. For each of those guys, we'll look at the NEP numbers for the teams that drafted them the year before they were selected and the two years afterward. From now on, the year before will be referred to as Year 0, the player's rookie year will be Year 1 while the sophomore campaign will be Year 2.

Doing this should give us a pretty good idea of what immediate effects there are of drafting an offensive lineman in the first round. If they can show improvement within the first two years, then the likelihood that this is a worthwhile long-term investment is fairly high.

The Results

After plugging in all of the numbers, the chart below is what came out. The column that reads "Year 1 Change" is the difference between that team's Adjusted NEP per play numbers between Year 1 and Year 0. The second column also is in reference to Year 0, meaning that it is the aggregate change from Year 0 to Year 2. I rounded them (for appearance's sake) to three digits, but when I use these numbers later, they will be expanded to five digits during any addition or subtraction.

Metric Year 1 Change Year 2 Change Pass NEP per Play +0.027 +0.033 Rush NEP per Play +0.014 +0.005

As you can see, even in the rookie seasons, the teams, on average, showed improvement over the previous year. This improvement occurred in both the passing and rushing games, although less so on the ground.

These numbers may seem small, so allow me to provide you with some context. This season, Cincinnati ranked 20th in Passing NEP per play with a mark of 0.05956 (this is usually just rounded up to 0.06, but we can better illustrate the change here using the non-rounded number). If they were to receive the Year 1 offensive lineman bump, that number would increase to .08641, ranking 16th in the league.

If we assign them the Year 2 total, this number further increases to 0.09265, which would have ranked 13th, right ahead of the Philadelphia Eagles. That's a seven-position difference in a category that goes a long way toward determining success (each of the top seven teams in Adjusted Passing NEP per play made the playoffs).

Who was second in this mark? The Dallas Cowboys at 0.28. Interesting.

As for the Adjusted Rushing NEP per play, the decline from Year 1 to Year 2 is a bit confusing at first. But, the nature of NEP may help explain that.

In general, rushing is less efficient than passing. This results in differences between Rushing and Passing NEP totals. For example, the average Adjusted Passing NEP per play from 2000 to 2014 was 0.03; the Adjusted Rushing NEP per play was -0.02.

This leads to a decreased variance in Rushing NEP totals as opposed to Passing NEP. In fact, the variance of the Adjusted Passing NEP per play totals over the life of the data was 0.0162 compared to 0.0044 for the Adjusted Rushing NEP per play. This at least provides some semblance of an explanation of why the number would drop from Year 1 to Year 2. Regardless, the teams were still more efficient both passing and rushing immediately after drafting an offensive lineman in the first round.

The Affect of Draft Positioning

So far, we've seen that drafting an offensive lineman in the first round does have a significant impact on a team's efficiency right away. This, though, is for the entire first round. There is a fairly large talent gap between the first overall pick and the 32nd. But how large?

To answer this, I just looked at the 48 linemen drafted anywhere from first overall to 20th, meaning that their team (under the current format and barring a trade) did not make the playoffs the previous season. These were the teams that needed that bump more than the others. And while it is a smaller sample size, I think the findings are still important.

Using only these draft picks, the average increase in Adjusted Passing NEP per play in the first season was 0.057, which is more than a 50 percent increase than when we included all of the first-rounders.

For the Adjusted Rushing NEP per play, the increase in Year 1 was 0.024 when just looking at the guys in the top-20 picks. This, again, was a decent chunk more than what we saw with all first-rounders.

The next step would be to reduce our scope to only top-10 picks. These were the teams that had seen some stuff the year before and needed to unleash the demons. Whatever they did, it worked.

The 24 teams that selected an offensive lineman in the first 10 picks saw an average increase of 0.089 in their Adjusted Passing NEP per play in Year 1. That was the difference between the 21st-ranked Arizona Cardinals this year and the 10th-ranked New Orleans Saints.

For Adjusted Rushing NEP per play, the number was 0.042 during Year 1 for top-10 picks. This was the difference between the New York Jets in 13th and the Miami Dolphins in 5th in the category.

This isn't just applicable to real-world football. It also works for the fake pigskin. As you can find in an article over at RotoAcademy, you will see a significant increase in the fantasy output of quarterbacks, running backs and wide receivers the year after their teams draft an offensive lineman in the first round.

The increases we saw for first-rounders in general were enough to justify the selection of a big-boned bully up front. The numbers for top-10 selections, though, can make your mouth water. If you're looking to build a solid offense, doing so through the offensive line is a pretty safe bet.

All of this is, obviously, dependent on situation. If you are -- willingly -- giving significant snaps to Kyle Orton, you'd be better off foregoing a big man to take a quarterback. But if you've already got your Tony Romo and maybe a dash of Dez Bryant, then why not?

During Sunday's broadcast of the divisional round game between those Cowboys and the Green Bay Packers, Fox's Joe Buck said that the selection of an offensive lineman in the first round was not one that fans would cheer. He was 100 percent right. But he shouldn't be. It's time to recognize how significant these trucks up front are and what they can provide for your team from day one.