Kerryon Johnson has been a revelation in Detroit. The rookie running back has done the unthinkable for the Lions and not only eclipsed the 100-yard rushing mark once but twice this season. As our own Kent Lee Platte pointed out earlier this season, he has been the most efficient running back has had since Barry Sanders.
The second-round pick is set to miss an extended period of time with a knee injury and Detroit will have to find a way to replace him.
But what are the Lions exactly missing out on?
Johnson has accrued 641 yards on 118 carries this season—averaging 5.4 yards per attempt. He has found the end zone three times on the ground this season.
The running back is a speedster with a good combination of speed and agility. He is mentally great as well, as his vision and decision making coming out of the backfield have been impeccable. His skill set lends to him being more of a quick outside runner rather than someone who bruises his way inside and that is exactly how the Lions have used him this year.
Whether it is running towards the left or the right, Johnson gets majority of his carries either off tackle or around the end. These runs allows him to use his combination of mental and physical tools to gash defenses for big gains and forces the front end of the defense to stretch to counter him.
It become apparent in the above graph that the Lions love running Johnson to the left more than anywhere else. That is because the left side of the field is where he has been most efficient.
A 32-yard run off of left guard and a 71-yard run off of right guard heavily skews a relatively small sample size.
Johnson has been incredibly efficient running to his left side. He averages over 8 yards a clip when going around the left end and has been gashing teams once he gets outside. He has done well running off tackle as well.
He has an opposite stat line when running to his right, though. Johnson is averaging just under 3.6 yards per carry running off the right end. However, his 4.1 YPC on attempts off of right guard trumps his 2.5 YPC when running towards the left guard.
There are a few potential explanations for this. Right guard T.J. Lang is probably the best player on Detroit’s offensive line. The Lions often pull him across the formation to seal the edge and create space for Johnson when he run outside. Even at his older age, he is better in space than rookie left guard Frank Ragnow. Left tackle Taylor Decker is a great run blocker when healthy, as well. This also explains why Johnson is so much better running off of right guard then left, as Lang is usually the one responsible for clearing up space when the running back runs towards him.
Another explanation is the disparity in unsuccessful runs Johnson has going towards his right. Whether it is the fault of play design, blocking or the running back himself, things go wrong a lot more often while he is heading right then when he is heading left.
Whether or not a run can be considered a “success” depends on specific game situations but for the most part on first or second down—where the rookie gets a majority of his carries—a 4-yard run can be classified as a success.
Only 50 percent of the running back’s runs off of the right end have been for 4 or more yards this season, compared to 73 percent when heading towards the left end. He has also been ineffective running inside for the most part. Only 41 percent of his carries off of left guard were of 4 or more yards and the number only slightly improves to 51 percent on the other side of the line. 57 percent of his runs straight up the gut have been of 4 or more yards as well.
Not only is Johnson most successful when running towards the left end, it is also where he generates by far the most big plays.
Almost all of the rookie’s chunk plays this season have come towards the left end and that has helped his yards per carry total. As seen in the above chart, 16 percent of his runs off of the left end have gone for over 20 yards. He is not just breaking off the occasional big run to the left end, though. His median carry total towards that side is sitting at five, which is higher than the entire third quartile of his runs off of left guard.
He has gotten bottled up when he tries to run between the tackles towards his left. Barring two outliers, his median and average run towards left tackle and guard fall right around or below the 4-yard mark.
While he has found success towards his left, Johnson has trouble getting anything past the line of scrimmage towards his right.
What stands out the most on the above box charts is Johnson’s stats when running off of right guard. While he averages around 4-yards per carry, he has a median carry of only 1 yard. Johnson has been feast or famine when running that direction, either finding room and earning a 6 or 7-yard pickup or getting absolutely stone walled at the line of scrimmage.
None of his median carries on either direction towards the right side are higher than 3.5. The yards per carry numbers are inflated by a few average runs, but, for the most part, he has not found any room to operate running towards his right.
The disparity between running to his left and right becomes even more apparent when you put the box charts side by side.
While the medians are about even, Johnson’s averages a lot more yards heading towards his left. His first and third quartiles are much higher on the left as well and the entire box seems to be shifted up a step. Even Johnson’s failed runs to the left seem to be better than his failed runs to the right.
There is a real chance Johnson’s rookie season is already over due to his knee injury. Whoever replaces him will not nearly be as good, and with T.J. Lang on injured reserve, it is hard to expect much from the Lions run game going forward. This leaves Bob Quinn, Matt Patricia and Jim Bob Cooter—or whoever may replace him—an offseason to figure out what has plagued this team when they run to the right. The fact that they have found success running to the left obviously means it is possible to replicate the success on the other side of the field. Whether it is personnel or scheme, Detroit’s run game has an interesting problem.