Have you looked at the Eagles roster? Both the Cardinals and Chiefs have significantly more talent than the Eagles. The Eagles are in a market that comes with much more pressure. Kelly has come in, worked with the front office to clear out a ton of dead weight, and made the most out of a big pile of crap. All while the entire league is staring and picking apart the fast tempo offense he is bringing in.
Big pile of crap? They have one of the top 5 RBs, good WRs and an emerging QB who's playing like a top 10 QB so far this year. The talent on offense is almost all people who were there before Kelly came in.
The defense is a big pile of crap, I'll give you that. It's no bigger a pile of crap than the Cardinals offense was when BASK took over.
Last year, the Eagles were 15th in total offense, 15th in total defense.
The Cardinals were 32nd in total offense, 12th in total defense.
The Chiefs were 24th in total offense, 20th in total defense.
This year, the Eagles are 2nd in total offense (+13) and 30th in total defense (-15).
The Cardinals are 21st in total offense (+11) and 6th in total defense (+6)
The Chiefs are 20th in total offense (+4) and 23rd in total defense (-3).
To me it's pretty clear cut which team has improved the most from last year.