I read something in the past week or so - I think it was on twitter but can't recall who - that said Kelly wasn't a failure as a pro coach, as much of his stuff was incorporated by several NFL teams throughout the league, but that he was done in by what a terrible GM he was and the personnel decisions he made (paraphrasing). Thought that was an interesting take.
So as somebody who lived through this nightmare, I'll give you what is widely believed in Philadelphia to be the full story.
He actually turned down their initial offer but after reconsideration he came aboard.
First year was magic from the start. Vick got hurt but the offense crushed with Foles playing qb. really seemed like he was an offensive genius; he got major production out of Racist Riley Cooper for cryin out loud haha. Everything seemed great and let me tell you how much the city of Philly bought into this guy. My wife and I sent him an invitation to our wedding. He didn't come (in fairness they had a game the next day, but hey, the Arizona cardinals were staying at the hotel we got married at, so im more bitter that larry fitz didn't respond to my twitter invite). The Eagles unexpectedly made the playoffs and were a Cooper drop away from beating the Saints at home in the wild card round. I'll never forget that game.
Year 2 is remembered as the year it started to go downward for him, even though they went 10-6 which was the same as the previous year when all as well. The issue was they started 7-2 and then lost a bunch of games that they shouldn't have. Word started to get out that the players didn't like him. He had a very authoritative style of coaching and this is the year he demanded full power and became the teams GM too. He would treat NFL players the same way he treated college players. This is the year he CUT DESEAN FUCKING JACKSON in the preseason because he wasn't a "yes Mr. Chip Kelly sir!" type. For a minute or two, the city was convinced that this guy just needs his "type" of players. He literally had our entire city convinced that players buying into his mindset was more important than talent. Which is sheer insanity. As fans, the general feeling was immense disappointment, but 10-6 really should get you into the playoffs, so we chalked it up to a fluke and it would be better next year.
The next years is when it all went straight to hell. He trades McCoy before the season. So that makes DeSean and LeSean that he has gotten rid of. Because he thought he was so much of a genius that he could succeed without their talents because they weren't scared little puppies who acted as his beck and call. And he traded Foles for Bradford. I'll never forget how Bradford ran the offense in the 3rd preseason game; we all thought Chip had done it again and found a star who just needed to get out of St Louis. Turned out not so much.
Now this is where I disagree with the concept that he was a good NFL coach just a bad GM; everything that made him special just went away. The offense they ran in 2015 was the most vanilla thing I have ever seen. They weren't even trying to do any of the things that had worked in 2013. A lot of fans think that when Chip didn't get to trade up for Mariota, his QB from Oregon, he just checked out. It does seem like that. He was fired after week 16 and is now universally hated in Philly. But I absolutely know that he sucked not just as a GM, but as a coach after his first season and a half. It was the strangest thing, it was like he just stopped trying. And go figure, getting rid of talent ends up biting you in the ass
Something about this guy has always seemed off. Everything from the fact that a vast majority of players hated playing for him to the not unwarranted accusations of racism (we don't have to go there, it is very widely discussed in philly. but lets just say that there was nothing he hated more than a cocky show boat black player and nothing he loved more than a "gritty" white player who tried hard). He had told the city that hes never been married bc hes married to football and then it came out that he once had a wife that he never talked about and nobody knew about. Just an all in all weird guy.
Now I GUESS you can make the argument that he was one of the first coaches to bring college concepts to the NFL and that may be valid, but lets not give the guy too much credit. The offense he ran his last year in Philly and his only year in SF were about as basic as playing Madden on Rookie level.
In summation; fuck Chip Kelly.