They weren't though, that's the point.
He was able to create the appearance of a Good Defense because he's a Heavy Heavy Blitzer, similar to how Manny used to create the illusion of Good Defense in 2016 & 2017. It was good havoc rate stats & lots of TFL's/Sacks, but in critical moments when we needed to get stops & the Defenses need to be more disciplined they would get shredded.
He also benefitted from having Lamar Jackson as our QB because of the system the Ravens ran offensively at that time, opposing Offenses didn't get as many possessions.
Martindale's Defense will work in college against inferior opponents, but against teams that have equal level talent, it's not gonna work. Especially considering the massive amounts of loss Mich is going to undergo due to the draft & Coaching turnover.
Plus, the jig is up on their scheme; they can't cheat anymore like they've been doing since 2021, so they playing field will be back even again.