Blake Corum suffered a tear to his left meniscus late last season, underwent surgery in early December, and was not yet able to cut as of March 13th but expressed then that he should be at that point in his recovery by June, would “be back definitely by fall camp”, and was “100 percent” sure he would play in Michigan’s season-opening game against East Carolina on September 2nd.

I’m not the injury analysis guy and I don’t want to speculate about whether Corum will actually be his old, healthy self by the start of the season rather than experience some reacclimation struggles on his return to the field that could affect his stock looking forward to next year’s NFL Draft -- let’s acknowledge that the injury was unfortunate, may or may not impact his play in 2023, and could give professional teams some pause about his long-term durability regardless. Because I want to take a wait-and-see approach with those things that my dual lack of a medical degree and any personal interaction with Corum keeps me from speaking intelligently on, this article will not speak to Corum’s value as either a devy asset or potential NFL draft pick -- instead, I want to evaluate Corum as a player, and specifically address some general (and mostly negative) sentiments about his on-field ability that I’ve perceived on Twitter and elsewhere in the devy space.

To start, I don’t think anyone would deny that Corum has been an awesome -- or at least very effective -- college running back. He was named third-team All-Big Ten at the end of a 952-yard rushing season as a true sophomore in 2021, and then followed that up with a 1463-yard rushing campaign last year that earned him consensus first-team All-Big Ten honors, a finalist performance in the run for the Doak Walker award (which Bijan Robinson ultimately took home), and unanimous honors as a first-team All-American. As he really only played in 11 of Michigan’s 14 games (he technically participated in 12 but left the Ohio State game after testing out the knee on two early rushing attempts), Corum’s yardage total represented a per-game average of 132.8, higher than for all but four guys in the entire country (DeWayne McBride, Mohamed Ibrahim, Chase Brown, and Zach Charbonnet) and including all returning college backs. He also averaged 5.67 yards per carry (an 81st-percentile mark among post-2017 college runners) after a 2021 season in which he averaged 6.65 (91st).

The common refrain you’ll hear in regards to Corum is that much of his production and efficiency alike can be attributed to the Wolverines’ offensive line. I won’t deny that the big boys at Michigan form an excellent group, but I think using them as a means to discredit Corum is both reductive and misguided.

To start, the most objective measures we have of offensive line play indicate that the Michigan group was good last year, but not so extremely good that Corum in particular deserves an asterisk to his rushing performance where other successful backs around the country do not. The 72.0 run-blocking grade that his linemen collectively earned from Pro Football Focus ranked 19th in the country and 14th among Power Five units in 2022, and Football Outsiders had them at 25th, 36th, and 32nd, respectively, in their Adjusted Line Yards, Power Success Rate, and Stuff Rate metrics (which measure average yardage blocked by the offensive line, success rate of rushing attempts with two-or-fewer yards to go on third and fourth down, and percentage of rushing attempts stopped at or behind the line of scrimmage, respectively) last season.

Those high-but-not-elite rankings speak for themselves to a certain extent, but to elaborate: there were 29 offensive lines that ranked higher than Michigan’s in at least two of those four categories last season, 18 that ranked higher in at least three of four, nine that ranked higher in all four of them. Among the latter two groups are the lines from UCLA, Ohio State, Oregon State, Georgia, Oklahoma, and Clemson, and I’ve seen far fewer (if any) claims that the talented running backs on those teams -- Zach Charbonnet, TreVeyon Henderson, Miyan Williams, Damien Martinez, Kendall Milton, Eric Gray, and Will Shipley among them -- should have their production or efficiency viewed with the sort of intense skepticism that Corum’s seems to inspire. Similarly, teams like Arkansas, Tulane, and Florida have offensive lines that outperformed Michigan’s in just as many of those metrics as they didn’t, and yet cries of “system running back” are nowhere to be found in regards to guys like Raheim Sanders, Tyjae Spears, or Trevor Etienne.

Still, the mere fact that other good (and even better) offensive lines exist does not necessarily mean that Corum is not a system running back fraudulently propped up by the performance of his blockers, but his own numbers as a rusher indicate that he’s adding value above and beyond what his offensive line offers him regardless:

Corum was outperformed by the other backs on the team by a yards-per-carry perspective last season (and barely outdid them in 10-yard run rate), but given the level to which defenses were packing the box against him, the degree of difficulty on Corum’s carries was far greater than what Donovan Edwards and the other Michigan runners experienced on theirs. Corum’s large workload combined with such heavy box counts made him just one of four Power Five backs to carry the ball 200 or more times and into defensive fronts at least 0.20 defenders heavier, on average, than what his teammates ran against, joined only by Sean Tucker, Xazavian Valladay, and Quinshon Judkins.

Box-Adjusted Efficiency Rating strips away much of the confounding effect that box counts have on raw efficiency numbers, and by that metric, Corum outperformed the per-carry output of the collective other Wolverine backs (and to a greater degree than both Tucker and Judkins did relative to their own teammates). More impressively, he smashed their output in terms of per-carry consistently, posting a Relative Success Rate that exceeds the career marks of all but one running back selected in the 2023 draft (Chris Rodriguez).

Further evidence of Corum’s value-adding comes via his performances in both missed tackles forced per attempt and Breakaway Conversion Rate, indicating high-level ability to evade tacklers and run in the open field, respectively, areas of running back play that have nothing to do with the effectiveness of the offensive line. He also gained 0.27 more yards on a per-carry basis than would be expected of a running back carrying the ball in the same situations that he carried it in last season according to Jerrick Backous’ RYOE model over at campus2canton.com, a higher mark than returning college runners like Shipley, Judkins, Etienne, Henderson, or Devin Neal posted in 2022, as well as higher than what 2023 draftees like Bijan Robinson, Kendre Miller, Devon Achane, Jahmyr Gibbs, or Charbonnet produced above expectation in their final collegiate campaigns.

Generational talent Bijan Robinson produced fewer rushing yards over expected on a per-carry basis in 2022 than what system running back Blake Corum did.

My film-charting process also does not reflect that Corum was simply along for the ride behind a dominant offensive line last season. Prior to the announcement that he would be returning to Michigan for his senior year, I had watched and charted six full Corum games representing 110 total carries across 2021 and 2022, and compared to the results of my charting for Raheim Sanders as well as sixteen runners in the 2023 draft class, Corum graded out as an elite and particularly impactful decision-maker on gap runs (which made up 63.6% of the charted sample, 63.3% of his workload from last season, and 66.5% of his career carry total thus far, in addition to being an increasingly large part of NFL running games):

Other than DeWayne McBride (who did his damage in Conference USA), no other back I’ve charted so far even comes close to Corum’s numbers in the above categories -- he and McBride are the only runners with a net vision grade above the 0.30 mark or an overall gap grade above the 0.70 mark, and Corum’s very low rate of neutrally-graded plays on gap runs indicates that -- beyond not just getting chaperoned down the field by his blockers like the “system running back” label would suggest -- he’s actually making more of an impact through his own decision-making behind the line of scrimmage than any non-Tank Bigsby runner that I’ve charted so far, and Bigsby’s low neutral rate is largely fueled by a lot of negatively graded plays on gap runs while Corum’s impact comes via mostly positive contributions. Stylistically, Corum is the opposite of the take-what’s-blocked-and-don’t-add-much-else kind of player that he has a reputation for being.

In addition to frequently adding value on gap runs through identifying viable extra-structural paths, Corum does a tremendous job of knowing when to go and when to slow behind the line of scrimmage: his net patience grade is a 0.10 that easily exceeds the population average of 0.06, and his net decisiveness grade of 0.16 does the same relative to the population average of 0.09 as well as trailing only Zach Evans’ 0.19 among studied runners. Additionally, Corum’s neutral rate in both of those categories is lower than for any other back I’ve watched, again indicating frequent value added through an advanced approach in the backfield. The only one of six decision-making categories that I grade in which Corum scores below the population mean on gap runs is tracking, and his neutral rate in that area happens to be a relatively low-impact mark 4.9% above the average.

I’ve also seen analysis that suggests Corum is either too small or too lacking in power in order to successfully translate his success as a runner to the next level. It’s true that Corum is not a huge dude at 5’8 and 210 pounds, but based on historical weight gain patterns for eventual NFL running backs, his seasonal measurements indicate that he’s likely to be 5’7 6/8” and 209 pounds at next season’s Combine, which would make him similarly-built to (and, in most cases, much denser than) past prospects like Aaron Jones, Kenneth Walker, JK Dobbins, Maurice Jones-Drew, Devonta Freeman, Ray Rice, and Javonte Williams (he also has explosive speed that should preclude him from Speed Score-related concerns even in the event that he weighs in closer to 205 pounds).

Owing in part to that fire hydrant frame, Corum runs with more power than you’d expect from an undersized back, as his through-contact performance against defensive linemen, linebackers, defensive backs, and defenders in general are all above-average relative to the other backs I’ve studied so far:

Corum’s 0.32 score versus defensive linemen is double Bijan Robinson’s mark of 0.16, and the other backs above the 0.30 threshold in that area -- Roschon Johnson, DeWayne McBride, Zach Charbonnet, and Kendre Miller -- weigh an average of 220 pounds. Similar breakdowns exist against the other two position groups, and Corum supplements that power and contact balance with a deep bag of evasive maneuvers and explosive cutting ability in 1-on-1 situations (see: 1, 2, 3).

In the end, I’m not sure what Corum’s meniscus injury will do to either his effectiveness on the field or his stock as a potential day two pick near the top of the 2024 running back class, but I do know that the idea that he’s some sort of system runner simply being carried to empty production by a strong offensive line is almost laughable. He has open-field juice, a blend of elusiveness and power that make him tough to bring down, and the intelligence to make effective decisions and add value behind the line of scrimmage. At his healthy peak, he’s as good as any running back currently in college football.