After the game, Ian Rapoport of NFL Network reported Darby suffered a dislocated ankle. ESPN's Adam Schefter reported Darby will undergo an MRI on Monday to determine whether he needs season-ending surgery on his ankle.
The injury came as Darby was fending off a block. He appeared to step awkwardly as he pursued quarterback Kirk Cousins, and he twisted the ankle in an unnatural manner before falling to the field.
The Eagles acquired Darby, 23, during the preseason in a trade with the Buffalo Bills and immediately tabbed him as their top corner. He notched 137 tackles and two interceptions across 29 appearances during his first two seasons in the NFL.
While he was superb as a rookie, he struggled in his second year, per Elliott Rooney of Pro Football Focus:
"Darby suffered from a sophomore slump last year, grading as the 66th-best CB with a PFF overall grade of 70.6. With seven pass breakups in 2016 Darby, ranked 28th out of 117 qualifying CBs but struggled to get interceptions, recording zero and dropping three potential INTs.
"Those numbers all pale in comparison to his 2015 rookie season, when Darby graded as the eighth-best CB in the NFL—his overall PFF grade of 86.3 was the fifth-highest grade by a rookie CB in the PFF era."
Regardless, he was clearly the Eagles' best option at cornerback, as that position was a major question mark coming into the season. If Darby misses a major chunk of the season, the Eagles will have to rely upon Jalen Mills and Patrick Robinson as the starters going forward.
While the Eagles addressed the position during this year's NFL draft, second-rounder Sidney Jones remains out with a ruptured Achilles, and third-rounder Rasul Douglas was inactive Sunday.