Maclin's injury in the first week of camp was a major blow to the offense. The team believed Maclin was poised for a breakthrough season. The injury, which occurred in a noncontact drill, took away one of the Eagles' most potent threats. The only silver lining is that it happened early enough that it did not hurt a specific offensive plan.
The player expected to replace Maclin was Cooper, who has taken an indefinite, excused absence. Kelly insists it's a life issue and not a football issue, but a prolonged departure from the offense will hurt the football team.
Even with Cooper, the Eagles lack a reliable No. 2 wide receiver to complement DeSean Jackson and Jason Avant in the slot. Their transition to a tight end-oriented system will be even more pronounced, and look for James Casey and Zach Ertz to play major roles with Brent Celek.
The encouraging sign for the Eagles is that Jackson has been perhaps the most impressive player in training camp. Jackson, who has not recorded a 1,000-yard season since 2010, seems to generate the top play in each practice.
"It was evident to us that he worked since he left here in June," Kelly said. "I think he's an explosive player. I think he's very difficult to cover in one-on-one situations. We're trying to figure out as we get through what his comfort level is, what routes he feels really good with. I think we're starting to get a feel for him."
The first two weeks offered no answer on who will start at quarterback Sept. 9 against the Washington Redskins. Nick Foles had strong days early; Michael Vick gained steam when the pads went on. The prospect of Matt Barkley's entering the competition has fizzled because the rookie has not received first-team snaps.
Kelly remains consistent in saying that he needs to see the quarterbacks against live competition, and he sees no benefit in forcing a decision without more information. That's why the preseason games will be so crucial.
"If you don't put people in live situations, it's tough to see where they really are," Kelly said. "I know I made the statement, everybody gets a big kick out of it, but a quarterback is like a tea bag. You don't know what you're going to get until the rush is live. . . . We'd like to get it done sooner. Again, we can't force it in terms of that."
If intangibles matter, Vick still commands respect from the locker room, and many of the core players have won with Vick. His public statements during the Cooper saga demonstrated leadership often sought in a quarterback.
Still, intangibles go only so far. The decision will be based on who puts the Eagles in the best position to win this season, and Kelly's evaluation remains incomplete.
Those who watched the Eagles allow 27.8 points per game last season might think the defense can't get much worse, but this year's group is unproven. The transition to a 3-4 defense can be termed an experiment at this point.
Trent Cole is getting more comfortable as a stand-up pass rusher, and Brandon Graham looks leaner and faster, yet both still do not appear fully comfortable in coverage. The end result of the transition, at least this season, might be more of a hybrid, 4-3 "under" defense that requires one outside linebacker to spend most of his time pass rushing and even lining up in the three-point stance at times. The games will be a good indicator of how some system and depth-chart questions will be answered.
In the secondary, it's unclear who will start at safety. Patrick Chung, Nate Allen, and Kenny Phillips are competing for two spots, with rookie Earl Wolff trying to make a push, and Kurt Coleman seeking to reemerge. Both Bradley Fletcher and Cary Williams, the expected starting cornerbacks, have suffered injuries.
Second-year cornerback Brandon Boykin has made a major leap after his first season, though, and was the most consistent cornerback throughout the first week of full-team practices. Expect Boykin to be a dependable player in the secondary in 2013.
Adapting to Kelly
It's clear this is Kelly's team, even if so many key players are holdovers from Andy Reid's time with the Eagles. The way the Eagles practice, talk, and approach each day is an extension of the head coach. In that respect, Kelly's transition is going smoothly.
But Kelly's line about quarterbacks and tea bags can be applicable to a head coach, too. The relationship between a coach and his players is often rosy when everyone is competing for a job and the team is undefeated, but it becomes more complicated when roster decisions must be made and potentially disruptive issues take hold of a locker room.
Kelly will be responsible for those decisions when the roster is trimmed and the depth chart is set. He is dealing with a divisive issue now with the Cooper fallout. Kelly maintained a strong voice publicly, hitting the right chords with his public comments. But how his voice carries in the locker room is most important, and the next few weeks will reveal how the Eagles respond - and how well Kelly understands the pulse of his locker room.
"I think we're pretty open in how we do things," Kelly said. "We're here for 14, 16 hours together as a group. So I think you can get a feeling on what a person's mood or how they're feeling is. We encourage guys to talk to us and to share with us. I think our players have."
Contact Zach Berman at email@example.com. Follow on Twitter @ZBerm.