Honestly Crosby and Capers have a couple of items in common, starting with some of their struggles being way over blown and not their fault.
Did Crosby have a slump year? Yes, but it was waaaay over blown, Crosby was normal inside of 40 yards and had a minor slump between 41 and 50 yards... Crosby big problem was that someone else kept asking him to line up for 50+ yarders... I believe Crosby was asked to kick 9 different 50+ yard FGs, in a year that the average kicker was asked to kick less than 2.
So how was Crosby's problem solved? The coach finally figured out he was the problem and they started attempting punt the ball into the other teams 20 yard line, instead of attempting the 50+ FGs. Did Crosby slump? Yes a little bit... but the bigger problem was the Coach.
Similar problems have happened with Capers, have his defense struggled? Yes... but honestly how often has Capers been given a complete defense?
The Packers defense has had some enormousness talent gap holes in them, which is not the fault at Capers at all... after the Super Bowl, they lost some guys and had almost no pass rush... then lost Collins and had nothing other than Burnett on the back end (and with all due respect, Burnett struggled a lot at FS), then losing the CBs. There has always been a HUGE hole in the Packers talent level at important roles/positions. That's not Capers fault at all, if anyone is to blame for that it's Ted Thompson. And this year we're going into training camp with big questions at important positions again on defense. The one that concerns me the most is the lack of quality depth at OLB... and then there is also the CB questions.
But it's like Rex and Rob Ryan... they are twins, and both run the same defense and have the same over aggressive style. I would even argue that Rob Ryan has played smarter with his team... when they both faced that Packers in the same season on different teams... Rex kept blitzing Rodgers over and over and over... and Rodgers kept burning him on it. Rob was smarter, when Rodgers burned him on blitzes, he adjusted and sent everyone back into coverage.
So why is Rex's resume look so much better than Rob's? Because of the GMs and talent difference... before becoming a head coach, Rex coached under some good GMs that got him more defensive talent (though they sometime struggled on offense talent), while Rob has coached under some really, really bad GMs and his defenses had very little talent to work with.