Defensive Rookie of the Year:
1. Tyrann Mathieu, Arizona Cardinals defensive back:
What's amazing about Mathieu is that he's already one of the NFL's most versatile and well-rounded defensive backs, playing safety in base packages and switching to cornerback in nickel and dime packages. I haven't seen a single cornerback who can match the third-round rookie in run support or blitzing.
Mathieu has also shown a knack for big plays, punching the ball out of Jared Cook's hands on a would-be long touchdown and tackling Nate Burleson short of the sticks on a potential game-winning drive. The Honey Badger is a key chess piece in Todd Bowles' defense, which rivals Seattle's for the No. 1 spot in Football Outsiders metrics.
2. Kiko Alonso, Buffalo Bills linebacker:
After watching Alonso dominate for the first three months of his career, it's hard to believe a player of his obvious athletic gifts lasted to the middle of the second round. Alonso ranks among the inside linebacker leaders in tackles, quarterback hurries, opponents' passer rating and yards allowed per reception. The Bills suddenly have an intriguing defensive nucleus under coordinator Mike Pettine.
3. Sheldon Richardson, New York Jets defensive end:
Richardson has teamed with Muhammad Wilkerson and Damon "Big Snacks" Harrison for a "Sons of Anarchy" trio that has emerged as the NFL's most dominant defensive line. While it's fair to knock general manager John Idzik for drafting Dee Milliner and Geno Smith, it's already evident that the Richardson pick was a home run. Outside of J.J. Watt, there isn't a better run-stuffing defensive end.
4. Star Lotulelei, Carolina Panthers defensive tackle:
Lotulelei's run-stop percentage (13.5) ranks first among all NFL defensive tackles, according to Pro Football Focus. The interior pressure from Lotulelei and second-round pick Kawann Short have freed up Carolina's Pro Bowl-caliber defensive ends and linebackers to make plays on the league's No. 1 defense. Check out Lotulelei's strength in the Vine clip below.
5. Eric Reid, San Francisco 49ers safety:
Despite an early-season injury to Patrick Willis and a month-long walkabout from Aldon Smith, the 49ers have been the stingiest defense in the league since Week 4. Reid deserves a lot of credit for that turnaround. His range, impact hits and ball skills stand out in a strong rookie safety class. The only concern is that he's already sustained two concussion and was shaken up again on a collision last week.