X Factor (noun): A hard-to-describe influence or quality; an important element with unknown consequences; also written X-Factor.
The Dolphins are thin at the position as it is, with Jenkins starting as the weak-side linebacker alongside middle linebacker Koa Misi and strong-side linebacker Chris McCain. Behind them is a mixture of replacement-level players and undrafted free agents, as the Dolphins didn't seek out the position in the draft.
Jenkins and his play were a major reason for this, as in 2014 he recorded 110 tackles, 3.5 sacks, two forced fumbles and a pass deflection in 15 games (14 starts).
That same performance will be needed out of him in 2015, and he's certainly the man to do it.
Jenkins should benefit from a stronger defensive line. Signing Ndamukong Suh and drafting Jordan Phillips will allow the Dolphins to use a 3-4 alignment from time to time, making Jenkins a pass-rusher, where Pro Football Focus graded him as the 14th-best pass-rushing outside linebacker in the league at 1.1.
His one deficiency came against the run, where PFF graded him out at minus-3.9. Due to the new defensive line acquisitions, that number could inch its way into the positives, especially since from time to time, Jenkins has shown himself to be very good against the run.
This play against Buffalo was one example of this.
Jenkins is at his best in pass coverage, and he'll be used in that role quite a bit. Jenkins grades out at 2.4 in coverage, which was seventh best in the league, per Pro Football Focus.
What should be interesting to see is if the Dolphins expand Jenkins' role.
Could we see him switch to strong-side linebacker and cover tight ends? While his 6'0" 243-pound frame might not seem conducive to it, he has shown himself to perform well in coverage.
It might also be a good idea to use Jenkins as a middle linebacker from time to time. However, the best way to do that would be in a 3-4 scheme with Olivier Vernon, Suh and Earl Mitchell up front, McCain and Wake on the outside and Misi inside with Jenkins.
There's a lot that Jenkins is able to do, and in his third year in the league, he should be much improved.
On defense, the names you will hear all season will be Cameron Wake, Suh, Olivier Vernon and Brent Grimes. But the linebackers, especially Jenkins, will be the biggest X-Factor of them all, for they will make or break Miami's defense.
Statistics provided by Pro-Football-Focus.com unless otherwise noted.