There's been alot of discussion on BGN about what should be the future of Juan Castillo with this defense. Most supporters of him staying as defensive coordinator have been throwing out rankings like they're 8th in YPG. However, due to 2 reasons, these rankings and numbers should not mean that Juan Castillo remains as the DC. As a sidenote, I wouldn't be opposed to keeping Castillo as a coach on this defense. I don't see him going back to offensive line, so maybe he could just be an assistant on defense to the coordinator (hopefully Spags).
1. Rankings don't matter if you don't consider the potential of the defense
Here's a scenario. You have two coaches. Coach 1 coaches a terrible defense with absolutely no talent, which should be in the 25-32 range in defenses. They end up as 13. Coach 2 has a defense with tons of talent and should easily be in the top 5. That defense finishes at 12. Is coach 2 better than coach 1 simply because his defense is ranked higher? Of course not. When evaluating a coordinator you can't simply look at the numbers; you also have to consider what the defense should have done and where they should have ranked. Only then can you truly determine how effective the coordinator was at getting the best out of his players.
The Eagles could have been at least a top 5 defense this year. If you look at where they were last year, and the pieces they added to the defense, they should have jumped more than 4 spots in the rankings (12-8). And this is why Juan Castillo isn't simply a good coach because they finished in the top 10. In reality, he still was unable to get this defense to be as good as they could have and should have been. With major acquisitions this offseason, our defense had an absolutely dominant defensive line. Had we managed our secondary better, it could have been in the top of the league. Our safeties and linebackers were not good, but Coleman played good at times and Rolle was great. Despite this weakness, Castillo should have been able to make up for 3-4 weak players with all of the surrounding talent we had. Our defense should have been better than it was, so does it really matter what ranking we finished at?
2. Even when the defense had improved, Castillo was still making the same mistakes
It has been said often how we should give Castillo credit for how well the defense played the last 4 weeks. However, if you look at the way the defense played, Castillo still made plenty of the same coaching mistake as earlier in the year. He continued to completely misuse his secondary, specfically his zone schemes with Nnamdi Asomugha. This is what bothered me the most about Castillo. He blatantly misused Nnamdi, it didn't work, then he continued with it.What Juan could have done is put Nnamdi in man, take out the opponents best WR for the game, which would take much of the pass coverage responsibilities off their struggling safeties like Coleman and Allen. This would utilize the best skills of his players (Nnamdi's man coverage abilities) while also avoiding exploiting their weaknesses. A good defensive coach is able to do this, yet Nnamdi did not adapt throughout the year to set up his defense like this. By using zone coverage, he put his safeties in a position where they were greatly relied upon to stop the pass, which was actually their weaknesses. This also put Nnamdi in an umcomfortable position and didn't allow him to use his talent. This ties back to my point before; Castillo wasn't able to get the best out of his players. In fact, he often put them in a position where they clearly were not fit and really restricted their ability to contribute.
The fact is that even though the defense played better doesn't mean Castillo coached better. He still made the same mistakes, such as putting Nnamdi is zone.The only difference is that we played some absolutely horrendous offensive teams. The Dolphins (without Moore for most of the game), the Cowboys (without Romo), the Jets, and the Redskins are 4 of the worst offenses in the league (check our djackfan10's post for the numbers). With Castillo making the same mistakes, he did not actually contribute to the improvement, but rather benefited from terrible offenses. If Castillo did not actually improve as a coach, why should these last 4 games buy him another year on this team.
For these reasons,I do not believe Castillo should remain as our defensive coordinator. It does not matter where the defense ended up if they should have been better. Castillo's strategies simply allowed the opponents to exploit our weakest aspects on defense. What good is it to be 8th if we should have been 5th? A good coordinator will use every scrap of talent of talent in his defense and bring the best out of his players. He will put his players in a position where they will be able to make plays. He'll make the defense better than it should have been. Castillo did the opposite. He put his players in a position where they were umcomfortable; he was unable to use the talent in this defense, and was unable to adapt.