When people talk about Chip Kelly’s offense, one of the most common buzz words they use is mobility. Although mobility helps running back LeSean McCoy burst through the line of scrimmage or receiver Jeremy Maclin get wide open, it is arguably more important for the offensive linemen who keep defenses out of the backfield.

Kelly has been fortunate to have exceptionally athletic centers at his disposal during his tenure at the University of Oregon and the Philadelphia Eagles. Eagles center Jason Kelce has the optimal combination of speed, strength, technique, and nastiness for a professional offensive lineman. Oregon fifth-year senior Hroniss Grasu—who played under Kelly from 2010 to 2012 and suffered a leg injury during last Saturday’s 51-27 victory over Utah—has been following Kelce’s footsteps as a pro prospect with impressive athleticism. Kelly’s use of mobile centers adds another dimension to his heralded offensive scheme.

Jason Kelce: Freak of Nature

It is no coincidence that McCoy struggled to find holes while Kelce was sidelined with an abdominal injury. When Kelce returned on November 2nd against the Houston Texans, his ability to punish second-level defenders was on full display on an inside zone run to the left.

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Kelly often uses the Sweep Read, which combines elements of the classic sweep play with the Outside Zone Read to take advantage of his center’s freakish athleticism.

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Kelce’s mobility is also useful in the passing game, particularly on screen passes. In Week 6 of 2013, Kelly called a screen pass to McCoy for the first play from scrimmage. Kelce got the Eagles off to a strong beginning.

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On one play in Week 3 against the Washington Redskins, Kelce’s natural athleticism and nastiness actually hurt the Eagles. Kelly called a screen pass to receiver Jeremy Maclin that could have been an 80-yard touchdown if Kelce had not make an illegal block downfield.

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Despite his mistake on this play, it is clear that Kelce is one of the most fearsome offensive linemen in the pros. He is just as much of a weapon for Kelly as any of the skill players because his unique athletic ability.

Hroniss Grasu: Rock of the Oregon Offensive Line

Grasu’s injury is particularly alarming for the Ducks, as he was the rock on which head coach Mark Helfrich relied while other offensive linemen suffered injuries.

Like his predecessor, Helfrich exploits defenses by using his center’s mobility in space. Grasu might not be quite as athletic as Kelce, but he is a weapon in his own right. He made a key block in a 48-14 victory against Wyoming on a Sweep Read.

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Helfrich also puts Grasu’s mobility to use in the bread-and-butter play of the Oregon offense, the inside zone. In Oregon’s 45-16 victory over Stanford, Grasu made a block at the second level that allowed running back Thomas Tyner to score a 21-yard touchdown.

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While he shows several signs of being an impressive pro prospect, Grasu is hardly a finished product. He has not yet mastered his hand positioning on defenders and lacks the level of nastiness Kelce displays on defenders.

Nevertheless, Kelce himself took several years to develop into an elite NFL center. The NFL team that acquires Grasu will have a tremendous opportunity to develop a high-caliber offensive lineman with impressive potential. With proper coaching, Grasu could be a valuable offensive weapon for years to come.

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