In the Patriots' Second (Patrick) Chung Dynasty, the veteran safety has obviously played a key in the team's defense. They basically created a new position for him as mostly a linebacker with coverage responsibilities against the opponent's top tight end.
The move was a revelation for the defense, and it revitalized Chung's career. He never displayed the instincts to play in space as a traditional strong safety, so the Patriots brought him closer to the line and allowed his skills as an attacking player to take over.
It's largely been sweet music. Chung has become one of Bill Belichick's favorite players, and he's taken over JerodMayo's role as the one player who constantly gets taken care of with his contract (Chung, 32, is still signed for another two years — unheard of at a contact position).
But as Chung's role increased, so did the importance of his position to the scheme. And with Chung's play declining in recent weeks — likely due to near-constant health issues — it appears the defense is suffering as a result.
That's why Chung and his spot appears to be a major swing position as the Patriots enter the postseason.