2. Mike Purcell, DL
Through Week 15, the Broncos' run defense is at the very bottom of the NFL. They are dead last, giving up over 146 yards per game on the ground. There are multiple culprits, here, but one name to watch in free agency is defensive lineman Mike Purcell. He is one of the main players that's struggled in that department, this year.
Purcell has played 373 snaps this year and has only been credited with eight total stops. That is a highly unimpressive ratio and one that the Broncos should use when evaluating Purcell's future with the team.
The 11-year veteran is going on 33 years old and, if you ask Pro Football Focus, he's in the midst of his worst season yet as a pro. They have given him an overall grade of just 48.8 on the year, with a run defense grade of 47.1. For those unfamiliar with PFF's grading system, typically you're doing fine if you're in the yellow. You're doing very well if you're in the green.
Purcell has only been given two single-game run defense grades in the green all season long. He is missing tackles at an alarming 24 percent rate, too. The Broncos can't afford an aging, underperforming defensive lineman to be back. It's that simple.