When a running back has a big game, you can count on him to thank his offensive line. But sometimes, it really is the running back who does the crucial work.

Isolating running back stats from the line's performance is difficult, but thanks to SB Nation's Bill Connelly, we're able to do that with the Highlight Yards statistic.

Highlight Yards means the yards a back gets on top of the 5 he should usually get if the offensive line does a good job. A Highlight Opportunity is any running play over 5 yards; the running back gets credit for all yardage beyond the initial 5.

The national player average is 5.22 Highlight Yards per Opportunity, while the most explosive players double that. For example, Indiana's Tevin Coleman averaged 9.79 in 2014. That meant any time Coleman's line got him 5 yards, he was likely to keep going for at least 9 more.

The full ranking of 2014 players with at least 50 Opportunities and a 6-plus average is below. First, here are the top seven power-conference backs who are returning for 2015.

(This isn't a list of the best backs, of course -- there's no Leonard Fournette or incoming true freshman even on the full list -- but the backs that have best demonstrated one particular skill.)

1. Nick Wilson, Arizona

8.33 Highlight Yards average, 74 Opportunities

Wilson was a stud freshman, rushing for over 100 yards seven times. He was particularly explosive against Utah and Arizona State, rushing for 218 and 174 with longs of 75 and 72. Since Arizona's backfield could be all his, he's the favorite to be Mr. Highlight Yards for 2015.

2. Nick Chubb, Georgia

7.92 Highlight Yards average, 100 Opportunities

After Todd Gurley was lost, Chubb didn't disappoint, winning freshman All-America honors and finishing with 1,547 yards despite not playing much early. He's known as a workhorse, but he had four games with at least one carry of 50-plus yards.

Via ESPN

3. Aaron Green, TCU

7.78 Highlight Yards average, 58 Opportunities

The former Nebraska transfer took on a bigger role in 2014 and now looks to take over TCU's rushing game as part of a College Football Playoff run. He averaged 7.2 yards per carry overall.

4. Josh Ferguson, Illinois

7.21 Highlight Yards average, 51 Opportunities

The long-overlooked Ferguson blew up for 190 on the ground against Texas State and averaged better than 6.3 overall in the season's two most crucial games, part of a boom-or-bust season.

5. Samaje Perine, Oklahoma

7.17 Highlight Yards average, 108 Opportunities

Perine heads into 2015 as one of the nation's most-hyped players. He rushed for over 1,700 yards as a freshman, including an FBS game record 427 yards against Kansas (here's how it happened).

6. Justin Thomas, Georgia Tech

7.06 Highlight Yards average, 83 Opportunities

The Yellow Jackets' season-changing quarterback also posted a passer rating of 153.91, better than Florida State's Jameis Winston, Mississippi State's Dak Prescott, and many others.

7. Corey Clement, Wisconsin

6.83 Highlight Yards average, 63 Opportunities

The next man up for the Badgers after Heisman finalist and first-round pick Melvin Gordon (who was No. 4 on the list below last season), Clement might be the latest all-world Wisconsin running back.

2014's players who averaged 6-plus Highlight Yards on 50-plus Opportunities (returning players in bold)