Not long ago, St. Louis Rams rookie running back Todd Gurley looked unstoppable.

He was ripping off 100-yard rushing games like he was still in college, and not even a Nick Foles-led offense could slow him down.

But his magic has worn off, and he's struggled of late -- based on the yardage totals.

We can blame the offense all we want, but was the writing on the wall the whole time?

Gurley's Great Start

If we expunge a six-carry, nine-yard performance in Week 3 from his record, Gurley's first four NFL games resulted in at least 128 rushing yards.

In those four games, he totaled 88 carries, 566 yards (6.43 per carry), and 3 scores on the ground.

Whew.

Since then, however, he has come back to earth.

Hard.

Gurley's last four games have resulted in just 219 yards on 70 carries (3.13 per attempt) -- though he has 3 touchdowns in that span.

Is Gurley slowing down? Is it the quarterbacks' faults? What's happened?

Or is he still just as good (or bad?) as he was when he started?

Gurley's Inefficiencies

It's hard to say that a player is inefficient when he's posting elite rushing numbers -- from a yardage standpoint -- but that was kind of the case for Gurley all along.

According to our Devonta Freeman's 23.32 was tops.) Per-carry, though, Gurley was as good as Freeman, both netting 0.15 per rush. Of 30 backs with at least 75 carries at that point, only Giovani Bernard (0.16) was better.

But...Gurley wasn't really on the same level as those guys.

Here's why.

Gurley's Rushing Success Rate -- the percentage of carries that actually resulted in positive NEP gains -- was just 36.17 percent. That ranked him 24th in the group. Out of 30.

Only two players at that volume had a positive Rushing NEP and a Success Rate below 40 percent: Gurley and Ronnie Hillman (a Rushing NEP of 4.92 and a Success Rate of 38.82).

Another important factor: only five players (Freeman, Gurley, Bernard, Mark Ingram, and Lamar Miller) owned Rushing NEP scores better than 5.00 at that volume. 

So, Gurley was extremely good at adding points above expectation level compared to his similar-volumed peers, but he was also extremely (read: extremely) dependent on big plays to secure his impact. Freeman (50.00 percent), Bernard (51.28 percent), and Miller (49.37 percent) were moving the sticks consistently. Even Ingram (40.68 percent, 14th among the 30 qualified backs) was fairly reliable in comparison.

Things Got Bad

A bad Success Rate can be tolerable when those big plays do hit, and that's what really made Gurley great.

But since his tear to start the season, those big plays haven't been there. Entering Week 12, Gurley's Rushing NEP was 4.82, meaning he lost 9.05 points from his cumulative score since Week 8.

On 61 carries, his Rushing NEP per carry was -0.15. Remember, it was 0.15 during his first five games.

Only 21 of his 61 carries added positive expected points to the Rams, so his Success Rate (34.43 percent) in those games was actually on par with his play earlier in the season.

The big plays just didn't come through.

Week 12 Woes

His most recent outing, a 9-carry, 19-yard game against the Cincinnati Bengals, wasn't any better. Per our initial scores from numberFire Live, Gurley's 9 carries resulted in a Rushing NEP of -3.85.

He lost 0.43 points on a per-carry basis.

Yikes.

His first carry (a two-yard tote to start the game) resulted in a NEP decrease. He was then stuffed on a 3rd-and-1 for a loss of 3 to end the drive, a big hit to his Rushing NEP.

On the team's second drive, Gurley racked up a four-yard carry on 1st-and-10, a slight hit to his NEP, but follwed it up with a two-yard loss. That's four unsuccessful carries in a row.

Gurley's 8-yard carry on a 1st-and-10 in the second quarter on the Cincinnati 13 was a NEP boost, but it was Tavon Austin who generated the big play (a 60-yard carry) and the eventual touchdown on the drive.

Gurley also saw a 3-yard carry on 2nd-and-11 with 2:44 left in the second quarter, a NEP loss. That made him one-for-six.

A one-yard loss to start the team's first drive in the second half netted another negative to his day, and a short gainer to open another drive made him one for eight. His final carry, 3 yards on 1st-and-10, was -- again -- a hit to his Rushing NEP.

What It All Means

Negative game scripts aren't good for running backs, and that's a lot of what Gurley can expect to see on this offense. But the bigger problem is that he can't create consistent gains for his team -- whatever the reason. (Yes, it likely has a lot to do with his offensive line, his quarterback, or the lack of receiving threats, but it's clear that he hasn't been overcoming these deficiencies.)

Even when things were looking fantastic and he was filling up the stat sheet, Gurley was inefficient in terms of generating reliable runs to move the NEP chains.

This doesn't diminish Gurley's initial production. If anything, it shines light on how good he was overall despite the lack of consistent success.

But to think that things have changed drastically isn't really the case. Gurley just hasn't hit any home runs lately, and that's causing the inefficiencies to show in the worst way.