Inside running game is staple for Arizona Cardinals, Bruce Arians

The Arizona Cardinals running game struggled for most of 2014. Between injuries and questionable play on the interior of the offensive line, the production wasn't great, as Arizona was 31st in the league in rushing offense and dead last in yards per carry.

I found something interesting about the running game on one of the NFL's stat databases the media can access, and that is the play direction report. The Cardinals ran the ball at an extremely high rate right up the middle, which seems to fly in the face of how you would like to use Andre Ellington, who can run between the tackles, but is much more effective when in space.

But it turns out that that is just how Bruce Arians does things with the running game in his offense.

In 2014, Arizona ran the ball up the middle on 142 plays, which was the sixth highest number in the league. They averaged 3.4 yards per carry up the middle, which was 29th in the league and right about their season average.

In 2013, they ran up the middle 193 times, which was the third highest total in the league. They averaged 3.59 yards per carry up the middle.

To see if this is something Arians only did with the Cardinals, I looked back at 2011 and 2012, when he was offensive coordinator for the Steelers and Colts (and also interim head coach in Indy).

Guess what? They ran the ball up the middle a lot, too.

The 2011 Steelers ran the ball up the middle 124 times, which was the 11th highest total.

The 2012 Colts did so 169 times, which was fourth in the league.

To compare, Ken Whisenhunt was not as reliant on the run up the middle. In 2012, they did so 120 times, but that was 15th -- very average. But it is also important to note that 2012 was the season when Levi Brown was lost for the season. If you look at 2011, when Brown was playing, it was a different story. They ran most often over left tackle -- 105 times, which was second in the league.

In essence, it will not matter who the running back is -- Bruce Arians will have his team run the ball up the middle.

There are a couple of things to take away from this. One is the need for a running back to be that battering ram up the middle. Andre Ellington is not suited for that. It is why Rashard Mendenhall was such a nice complement. Maybe that will be Kerwynn Williams. Perhaps it will be a new running back in the draft or in free agency.

It also means that the Cardinals will need to rely on their center to be at least an able run blocker. Pro Football Focus gave center Lyle Sendlein a -14.6 run blocking grade for the season. There was the belief he wore down as the season went on.

Now that we know the trends, we can see where the Cardinals will hopefully look to improve on the interior line and find a bigger, more able back to run up the middle, as it is clear that Arians will call the middle run, no matter who he has at running back.