After a Week 6 game against Pittsburgh, Cleveland's rushing attack ranked seventh in the NFL according to our metrics. Today, just three games later, the Browns come in at 25th.

I thought a drop off like that could only come in the form of Kirk Cousins, but the Browns are proving me wrong. With an Adjusted Rushing Net Expected Points (NEP) score of -11.96, Cleveland's played roughly 20 points below expectation on the ground over the last three weeks, becoming one of the worst running offenses in the league.

What happened?

The Secret World of Alex Mack

I can't tell you how excited I am to finally use this subhead. Unfortunately, it comes at the expense of an Alex Mack - not the Nickelodeon one - broken leg.

The Browns' center had surgery on said leg after the team's contest against Pittsburgh, so he's naturally not been playing since Week 6. You may claim this is a correlation does not imply causation issue, but there's no doubt that Mack's absence has played some sort of role, as the Browns have dropped 18 slots in rushing offense rank since he went down.

You could argue, too, that the play-calling has been more pass-heavy over their last three games. Take a look at the chart below noting the pass attempts versus running back rush attempts for Cleveland this season.

These raw numbers aren't the end-all to this argument. Teams will often flip play-calling tendencies due to inefficiencies - if they're not running the ball effectively, coaches aren't going to tirelessly keep pounding the rock, and vice versa.

That's where I think this discussion gets interesting. We know that Mack being out of the lineup hasn't been a good thing for Cleveland, but there are countless factors that can contribute to less success.

How about - I don't know - quarterback Brian Hoyer?

Through the first six weeks (five games) of the season, Hoyer was playing well. Over the last three weeks, Hoyer's been more Gabbert-like than arguably any other signal-caller in the league.

Before we dig into these numbers, it's important to note that, during Weeks 7 through 9, the Browns faced the Jaguars, Raiders and Buccaneers. Those teams rank 21st, 28th and 32nd against the pass per our metrics, respectively.

Meanwhile, Hoyer's seen his Passing NEP drop by nearly eight points despite the cakewalk schedule. His Passing NEP per drop back average went from 0.25 to -.07, and his Success Rate - the percentage of positive NEP plays from a player - has dropped about 7 percent.

The way he's performed over the last three weeks would equate to a -42.34 Passing NEP over a 16-game season which, in 2013, is about where E.J. Manuel and Eli Manning finished. And, again, Hoyer's done this against three of the worst pass defenses in the NFL.

The Browns running issues aren't just because of Alex Mack. They're also because of Brian Hoyer. After that game against Pittsburgh, Cleveland's aerial attack ranked 10th according to our metrics. It now ranks 25th.

Perhaps a key reason for this, too, is Alex Mack. But, man, if losing a center forces your offense to drop from the 9th-best one to the 23rd-ranked one in the league in just three games, then you've got some big issues.

The fact is, I think two things are happening. First, the Browns offense is regressing a bit. No one saw them being as efficient as they were to start the year, and this could simply be a little closer to who they are.

Second, while we look to the running backs and offensive line as an issue - probably because that's what we care about with the Browns in terms of fantasy football - we can't ignore how absolutely terrible Brian Hoyer has been over his last three games. Awful. Such poor quarterback play does a rushing offense zero good. And against bottom-tiered secondaries?

Is it Johnny Football time yet?