The next two are seventh-round draft pick Jordan Poyer and veteran Trevard Lindley, who was out of the NFL last season. They'll both need to play significant time in Thursday's game and have an improved chance of making the roster. The lack of depth also will prompt the Eagles to search the waiver wire and the trade market. Expect them to be active when cuts are made on Saturday. Teams usually keep five or six cornerbacks on the 53-man roster.
"We are concerned," Kelly said. "Postgame on Thursday will be a big day to see what comes available. Our whole thought is we'll play with what we've got. But this is a concern."
Kelly did not have a timetable for the return of Hughes or Marsh. Fractured hands take about two months to heal, although returns vary based on the rehabilitation schedule and whether the player can perform with his hand wrapped. The Eagles must cut the roster to 53 players on Saturday, and they cannot afford to use too many roster spots on replacement-level players who cannot play because of injuries.
Kelly said the injury timetable would be a big factor in determining whether the ailing cornerbacks make the roster. Marsh is a former third-round pick entering his third season and Hughes was a contributor on special teams last season, but neither has the track record to merit significant patience.
"When can they come back?" Kelly said. "When can we expect them? Is it back Week 3, is it back Week 8? All of that has to go into the final decisions of who is playing."
The cornerbacks struggled last season even though former Pro Bowlers Nnamdi Asomugha and Dominique Rodgers-Cromartie were starters. Boykin was the No. 3 cornerback. The Eagles replaced Asomugha and Rodgers-Cromartie with Williams and Fletcher, two tall cornerbacks who are better tacklers, albeit with lighter reputations and salaries than their predecessors. Boykin remained, but the Eagles did little to add depth beyond those three.
Marsh and Hughes remained under contract, so the Eagles counted on their development. They drafted Poyer, although the seventh round represents a minor investment. Neither Lindley nor Poyer was an NFL player last season.
Cornerback was already a weakness even before the Eagles suffered these injuries.
Even though they're expected to add at least one cornerback before the Sept. 9 opener against the Washington Redskins, the Eagles could still keep Poyer or Lindley.
Lindley, 27, played 11 games for the Eagles in 2010. He went to camp in 2011 and 2012, and was close to making the roster last season. He's good enough that the team keeps bringing him back, although he has not done enough to merit a roster spot in the past or a noticeable promotion throughout training camp.
Poyer is a player to watch, because he was a first-team all-American last season at Oregon State and can develop while contributing on special teams. He started camp slowly before improving as the summer progressed, but he still must prove worthy of a roster spot.
"Coming into this game, it's a big opportunity for me to really establish myself," Poyer said. "They're talking [about playing Poyer] early first quarter, so I can get a real flow for the game and show the coaches what I could do."
Click here for complete coverage of Philadelphia Eagles training camp.
Contact Zach Berman at email@example.com. Follow on Twitter @ZBerm.