One area that has to be addressed, and it must be addressed on both sides of the ball, is the Eagles' ability to sack the opposing quarterback and to keep their own quarterback from being sacked. The team wasn't very good at either of those in 2013. It ranked 26th in sacks allowed per pass play on offense and 31st in sacks per pass play on defense.
From the defensive perspective, that was one reason the Eagles targeted - and reached for - outside linebacker Marcus Smith in the first round of the draft and added two defensive linemen in the later rounds.
From an offensive perspective, that's why it wasn't good news to learn that right tackle Lane Johnson was popped for violating the NFL's performance-enhancing-drug policy and will miss the first four games of the season.
If the Eagles are going to improve in Kelly's second season, there is definitely a lot of room for that improvement, as the coach says. But keeping Nick Foles clean while getting ahold of the other guy's quarterback is vital to continued success.
"I think we're going to focus on pass protection and try to tighten things up," guard Todd Herremans said. "There were a couple of different factors that went into the 46 sacks, but not everyone sees all of that. We play offensive football, so when we get sacked, the whole offense gets sacked."
The Eagles did a slightly better job of preventing sacks with Foles at quarterback in 2013 than when Michael Vick was in the game. Vick tended to hold the ball longer while Foles was more apt to dump the ball off when trouble arose. Some of that was balanced out by the fact that Vick could elude rushers more easily than Foles, but Vick still absorbed 33 percent of the season's sacks despite throwing only 28 percent of the passes.
Nevertheless, the most costly sack of the year took place when Foles suffered a concussion against the Cowboys that forced him to leave the game and miss the next game as well. The correlation between allowing sacks and winning was obvious for the Eagles last season. Twenty-two of the sacks, nearly half, occurred in the team's six regular-season losses, and 24 in the 10 wins.
The advantage was just as pronounced on the defensive side, where the Eagles couldn't get consistent pressure and finished the season ranked 32d in net passing yards allowed per game.
"Our pass rush has to get better. Dead last, it goes without saying, but it's all facets - the pass rush, the blitz, the play-calling, the coverages," defensive coordinator Bill Davis said. "Our defense wasn't great last season, by any statistical category, but if we can start this season the way we finished last season, we'll keep climbing."
Having Smith join Connor Barwin, Trent Cole, and Brandon Graham at the outside linebacker position should help. At least, that's why he was drafted.
"He's got speed coming off the edge," Kelly said of Smith. "We thought having a pass rusher was a big thing for us."
There were the predictable transition pains for the defense as it switched to a 3-4 base alignment and a steep learning curve for players such as Cole, who went from end to linebacker, and Fletcher Cox and Cedric Thornton, who went from tackle to end. Add the inability of Isaac Sopoaga to clog the middle at nose tackle and the tall order given his replacement, rookie Bennie Logan, and those pains were apparent.
"Pass rushing in the 3-4 is an interesting component," said defensive line coach Jerry Azzinaro. "There are a lot of parts to it. What picture do you present? Who's the fourth rusher? When is there going to be a fourth rusher? How is the offense working against you?"
It is a game of deception, and sometimes a 3-4 defense has to be judged differently. But when it is third down and a passing situation, all NFL defenses have four pass rushers with their hands in the dirt. Opponents converted 40.3 percent of their third-down opportunities against the Eagles in 2013, which ranked them 24th in the league. It wasn't all about not being able to pressure the quarterback, but a lot of it was.
So, as training camp opens and the coach says the team needs to improve everything, remember that some parts of the everything are more pressing than others. And put sacks near the top of that list.
"Everybody wants it to be a revolution, but it's an evolution," Azzinaro said.
Little by little, practice by practice, day by day.