The Eagles hung tough for more than three quarters, but their offensive improvement was undone by a woeful defensive performance that resulted in a 42-30 loss to the Chiefs on Sunday at Lincoln Financial Field. Win, lose, or draw, here’s what we learned:

Jonathan Gannon has a ways to go as a defensive coordinator. Few expected the Eagles to shut down the potent Chiefs offense. Most fans would have probably accepted around 30 points allowed had the defense forced a few field goals or punts. Patrick Mahomes, Tyreek Hill, and Travis Kelce — those are just Kansas City’s perennial All Pros. But Andy Reid has talent and speed deep into his pool of skill position players. Gannon was always at a disadvantage. His unit allowed 41 points to the Cowboys a week ago and got manhandled in the run game, with the ineptitude of Nick Sirianni’s offense partly attributed to the struggles.

But there was little rationalization for the defense’s ineffectiveness Sunday. The offense mostly did its job, at least in terms of keeping the ball away from Kansas City. It didn’t capitalize in the red zone — converting only 3 of 6 possessions into touchdowns — but Sirianni’s group could have benefited from one or two stops. Gannon’s game plan made sense on paper. He employed deep zones to account for Hill and shaded coverage toward Kelce. He would take his chances against the Chiefs’ run offense and a relatively young interior offensive line. He would accept some bend in the hope that his defense wouldn’t break. But the Eagles — especially their front seven — couldn’t contain running back Clyde Edwards-Helaire on early downs. The linemen didn’t get off enough blocks, and the linebackers didn’t fill enough gaps. And once the Chiefs established the run, Mahomes was free to pick his spots through the air when Gannon switched to man coverage or blitzed.

Hill (11 catches for 186 yards and three touchdowns) was mostly the beneficiary. The speedy receiver found holes in Gannon’s zone with slant and curl routes, but he did some of his damage vs. man. He beat cornerback Steven Nelson on a 32-yard fade route. And three plays later, on third-and-goal, Reid schooled Gannon when the defensive coordinator kept two linebackers on the field vs. “11″ personnel (three receivers and one tight end). He went empty and got Hill matched up against linebacker Eric Wilsondoh! — and the result was a predictable six points. In the previous two seasons, we saw Jim Schwartz increasingly use dime personnel vs. 11 in third-down situations. Gannon hasn’t utilized dime much, if at all, this season. He may feel he doesn’t have a sixth defensive back to fill that role, but his linebackers haven’t held up in coverage. All told, the Chiefs converted an astounding 9 of 10 third downs.

There were several other examples of when Mahomes took advantage of Gannon’s scheme. The coach did blitz three times, but the quarterback completed two of three passes against extra rushers — the last a 44-yard touchdown dagger that left Hill alone vs. safety Anthony Harris. Gannon was often damned if he did and damned if he didn’t, but Reid was almost always a step ahead and the first-time coordinator’s inexperience showed.

» READ MORE: Andy Reid says goodbye to Philly and the Eagles by torching Jonathan Gannon’s defense

The defensive personnel, especially at linebacker and safety, is as much the issue as the scheme. I had concerns when Gannon unveiled 3-4 looks early in training camp. I understood his motive. He wants to be multiple up front so that the Eagles aren’t predictable. But I wondered if he had the correct personnel for the scheme. Fletcher Cox and Brandon Graham played in an odd-man front for three seasons when Bill Davis was defensive coordinator. But Cox was younger then, and Graham played mostly as an outside linebacker. Before the latter’s injury, Gannon had him as the five-technique in the 3-4. Graham was competent enough to fill the role, but Josh Sweat, Ryan Kerrigan, and Tarron Jackson have looked out of place in that spot.

Graham’s injury was a blow. But the Eagles’ depth on the defensive line was supposed to be their greatest strength. Javon Hargrave and Sweat have played well, for the most part. And Cox — more on him later — still garners attention, if not quarterback pressures. But Derek Barnett has been mostly a no-show, and the second unit — especially interior linemen Milton Williams and Hassan Ridgeway — has been subpar. I’d lean more on scheme than personnel for the issues up front. But on the back end, particularly in the middle of the field, the talent, or lack thereof, has been the biggest problem. Where have we heard that before? Wilson and Harris were clearly Gannon guys having played in a similar system with the Vikings. Despite Wilson’s interception of Mahomes on Sunday, Wilson and Harris have been among the two worst performers on defense. Linebackers Alex Singleton and T.J. Edwards are serviceable run defenders, but they’ve been easy to expose in the pass.

Rodney McLeod’s return gave the Eagles their leader in the secondary. He did fine on Sunday, but he and Harris have primarily been post safeties in their careers. Gannon needs a versatile piece — see: Malcolm Jenkins — who can play multiple spots and fill that quasi-linebacker role in dime. Marcus Epps and K’Von Wallace aren’t the answer. Cornerbacks Darius Slay and Nelson have held up, but smart offensive coordinators and quarterbacks will just throw away from them. Gannon has to find a way to force throws outside. He has an opportunity to right the ship against a Panthers offense that will be without star running back Christian McCaffrey on Sunday. If he can’t stop the hemorrhaging soon, it might be time to sound the alarm.

Fletcher Cox’s regression isn’t anything new. The Eagles Pro Bowl defensive tackle hasn’t been a one-man wrecking machine in years. I wrote about his decline and internal concerns about his future in June. Cox was and is still a player to be reckoned with. Offensive lines are still sliding interior protection to him more than to other D-linemen. But that has always been the case — more in past years — and he still found ways to make stops and get to the quarterback. I wonder how much of his struggles — he doesn’t have a single sack or quarterback hit this season — relates to scheme. Asked about his responsibilities possibly changing early in camp, he said then that he’d only been asked to play three-technique. But that eventually evolved to include various roles.

He shouldn’t allow that to affect his performance, but Cox doesn’t fight through double teams like he used to. And he isn’t winning many one-on-one matchups. He’s also hit the 30-year-old benchmark. Time waits for no one. It isn’t his fault that his salary hasn’t matched his production, though. Howie Roseman kicked that can down the road far too often, in terms of guaranteed money, and in the process allowed Cox to have far too much internal influence. But unlike with Schwartz, Sirianni hired a defensive coordinator whose system doesn’t really make the defensive tackle the focal point. I wouldn’t bet against Cox shaking off some of his doldrums. He may have a standout outing or two or even three. But consistency has long been an issue, and increasingly so.

Jalen Hurts can win in this league, as long as his play-caller understands his strengths and weaknesses. I tackled the head coach’s game management in my column off the game, but Sirianni did construct a solid game plan. Unfortunately, it made last week’s mind-boggling strategy against the Cowboys look that much worse. Where were the motions, the play-actions, the quarterback runs, and the quick timing patterns last week? Shouldn’t that be the blueprint with Hurts still young and learning? Yeah, I get that you have to account for a defense’s tendencies, and that there are reasons behind the usage, or lack thereof, of certain tactics. But this isn’t about your system, or about impressing the rest of the league with your downfield route concepts. It’s about putting your players and especially your quarterback in the best positions to succeed.

The Chiefs defense might be as bad as the Eagles. I couldn’t quite understand why defensive coordinator Steve Spagnuolo sat back rather than crowd underneath and force Hurts to go long more. He wanted to blitz the youngster, obviously, and did fairly well when pressure was applied. Hurts completed just 8 of 16 for 76 yards when Spags sent extra rushers. But he also tossed two touchdowns and was sacked only once. Nevertheless, Sirianni exploited the Chiefs linebackers and used some motion at the snap to divert eyes. He sprinkled in enough run plays to keep the linebackers honest.

But the best change he made was employing a short passing game, that included moving the pocket, to give Hurts easy reads and passes to build his confidence. And as the game progressed, the Eagles opened up the offense and he delivered with several strong throws. Was he great? Sirianni said it was one of the best performances for any quarterback he’s coached. That may be hyperbole. Hurts missed several red-zone passes he needed to make. He nearly tossed a couple interceptions. But he kept moving the chains with crisp throws and if not for three penalties could have matched Mahomes with five touchdown passes.

It was an encouraging rebound after a brutal start in Dallas. Hurts just has to keep stockpiling positive results. And more importantly, Sirianni has to allow for the possibility.

» READ MORE: Eagles’ Jalen Hurts after loss to Chiefs: ‘There are no moral victories’

Extra points. Lane Johnson’s absence couldn’t have come at a worse time. The Eagles were already down three starters on the offensive line, and Jack Driscoll had spent all week preparing to make his first start of the season at right guard. But O-line coach Jeff Stoutland had no choice but to move Driscoll to right tackle and bump Nate Herbig up at right guard. If the Eagles had pulled off the upset, the O-line’s performance might have led most stories. The quick passes aided the unit, but there were several third downs when Hurts had ample time. … Sirianni offered little information on why Johnson was a late scratch. He said he found out he wouldn’t be playing just a few hours before kickoff. He cited a “personal situation” for why Johnson couldn’t go and wouldn’t say if he was at the Linc at any point. Johnson popped up on the injury report with an “ankle” last week. He underwent surgery last season. It’s unclear if it’s the same ankle. He’s had myriad ankle issues since 2018, when he almost didn’t suit up in London, to the dismay of Roseman, who berated him in the locker room. Johnson did play, but lasted only a brief period before re-aggravating the injury. … DeVonta Smith caught seven passes for 122 yards for the first 100-yard outing of his brief career. The receiver had a couple standout grabs and is already the best receiver the Eagles have drafted in years.