That’s the subject of my new SB Nation Philly column.

I wasn’t able to cover every angle in there. I easily could have doubled the column in length as I tried to hit on everything. Wanted to keep it somewhat readable. I’ll address a couple of other angles here.

Mike Krzyzewski is the first coach I ever heard say that a coach’s primary responsibility is putting his players in a position to succeed. Simple idea, but too many coaches miss the boat. You want your players to succeed so you use them in a role they can handle. That isn’t to say you can’t experiment. Sometimes you have to do that to find things out. The point is not to rely on a guy to do things he simply can’t on an ongoing basis.

How has Castillo done in this regard? Mixed bag. The DL all fit the new scheme. No complaints there. Antonio Dixon is struggling a bit, but he’s just got some technical stuff to work through. Some will fault Castillo for what he did at LB. I understand the thinking behind moving Chaney to SAM. That’s your best athlete. Why not try to use him on TEs, a perennial problem for the defense? Disagree with the move if you like, but there is some logic to it. This wasn’t some blind stab in the dark.

Castillo’s use of the DBs is more confusing. I understand that he’s got a lot of pieces to try and work in, but there doesn’t seem to be a clear plan. The plan at DL worked fine. LB didn’t go so well, but there was a plan. DBs…I’m not so sure.

I flat out don’t understand the whole switching the name of SS and FS. That’s just weird. Okay, move on from that. We’ve got 3 good CBs. We tried DRC in the slot. That doesn’t look so good. He’s more of an outside cover guy. I can live with trying it out, but I’m not sure there is much wisdom in doing it any more. You’ve got Joselio Hanson, a natural slot corner. Put him in there. Nnamdi has shown the ability to play inside. Move him in and put DRC out wide. They did some of that last week.

Injuries supposedly were the reason that Nnamdi didn’t cover Tony Gonzalez in the ATL game. Okay, I’ll buy that, but with all the CBs healthy this week we better not see Moise Fokou as the primary cover guy on Vernon Davis.

As for not letting Nnamdi press enough…that’s tough to evaluate. He is playing some bump ‘n run, some press, and some zone. We do need a mixture. Oakland is the only team that goes 99% man to man and their DBs will tell you it’s dumb because offenses know what the coverage will be. That makes it easier to gameplan. You must have a variety.

Does anyone have numbers on how much Nnamdi is pressing vs playing off? If he is playing press coverage less than 50% of the time, then that isn’t enough. That should be his primary coverage style. That’s where he excels.

Juan has some very good pieces to work with. He’s got to find the right combination. And that leads to a key point. All coaches do some tinkering early in the year. Last year Dom Capers had to figure out how to use his personnel with the Packers. He moved guys around until he finally got the right group on the field. Dom wanted to play a lot of Nickel, but early on the Packers were getting gashed by the run. They couldn’t stop people. He kept making lineup and schematic adjusments. In the first 8 games the Packers allowed 124 rushing yards per game. In the last 8 games only one time did a team run for that many yards.

Think about how Jim Johnson tinkered with the lineup when he was in charge. In 2002 he was all over the place with how he used Barry Gardner and Levon Kirkland at MLB. In 2003 the team traded for Mark Simoneau and introduced him as the new WLB. Something like a week later the team signed Nate Wayne. He was introduced as the new WLB and Simoneau moved to the middle. In 2004 the whole world wanted Jeremiah Trotter to be the MLB, but JJ waited until after the Steelers debacle at midseason to make that change. In 2006 JJ replaced Matt McCoy with Omar Gaither at midseason. In 2008 JJ replaced Omar Gaither with Akeem Jordan at midseason.

Mixing and matching lineups is nothing new to the Eagles or any other team. Coaches aren’t idiots. They have a variety of reasons for making moves that seem odd. There is a specific thought process going on. Sometimes it is to address a weakness. Castillo thought Chaney could help us cover TEs better if he played at SAM. That didn’t work. Sometimes the coach moves one player in order to get another guy on the field in that spot. Howard Mudd did that with the OL. He liked 2 LGs, but no RTs. Solution? Move Todd to RT and let Evan Mathis play LG. That’s worked well so far.

Juan shuffled the LBs last week. This week he replaced Casey Matthews with Brian Rolle. He also replaced Kurt Coleman with Nate Allen. Let’s see how the revised lineup does. There is also a chance Darryl Tapp gets back on the field. That will help the DL rotation, which should help the pass rush be more effective in the 4th quarter, something that hasn’t been the case in the 2 losses.

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I fully understand the criticism of Castillo. His unit has underachieved and has blown leads in consecutive games. I don’t get the notion that he’s shown himself to be incompetent.

Back in 1998 the Eagles offense was horrible. I’ve written and talked about it plenty of times. The group literally could not function correctly. It was lacking in talent, but that group scored just 1 TD in the first 3 weeks of the season. They had just 2 games of 300 or more yards prior to December. Dana Bible ran the offense for a while, but Ray Rhodes replaced him around midseason because the group was so dysfunctional. Bible is a fine college coach, but was clearly in over his head in the NFL. He was incompetent.

I don’t see anything like that with the defense. There are some things going right. The defense has looked outstanding for parts of games. You can see the potential the group has. Juan has some stuff to build off. If he can get the group to play in the 4th quarter like they do in the 2nd and 3rd, the defense might turn out to be pretty darn good.

Can he do that? I hope so. I sure can’t say “yes” with any sense of confidence. Right now Castillo must show that he can solve problems. He’s made the lineup changes. Now he needs to show us good results. There aren’t a whole more changes to be made. This is the group. They have to get the job done.

I’d be screaming for Castillo’s head if I thought the guy was incompetent and he was the one thing holding our defense back. As I point out in the SBNP column, coaches like Gregg Williams, Dom Capers, and Bill Belichick all have worse defenses than us.

This week is critical. We’re facing a poor offense. If Castillo and the D can’t handle the Niners, then we’ve got some serious issues to deal with.

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Reuben Frank did an interview with Castillo a couple of days ago. Juan needs some coaching on how to handle the media. He doesn’t realize that telling us about effort and hard work is somewhat meaningless. We get it, Juan. No one questions your intentions, work ethic, or drive. That’s not the issue. We need answers on defense. I don’t expect him to give us the playbook, but he’s got to figure out how to sell his ideas to reporters. The “we’ll work harder” thing has been used up. Learn some new non-answers that other coaches use. Talking while saying nothing is an art form.

If the defense starts to play better, then he’s welcome to talk about effort and hard work as much as he wants. That’s a fair deal.