I appreciate that view as a fellow cat fan and I mean no disrespect. But as a guy raised in Indiana by a defensive specialist, it gets my hackles up when people think defense is so simple that people pick up a few principles and then job done. Defense is a complex, never-ending job, and defensive masterminds are a very hard get. John Wooden won a lot of natties with it, and teams that can make stops get wins in March. A good example is Wooden's legendary press at UCLA. Plenty of people saw it, filmed it, and experienced it. But nobody ever replicated it. The teaching and the nuances were so hard to master, the knowledge so specialised, and the muscle memory so intensely trained that it it remains a one-of-a-kind feat.
Now some numbers based on our defensive efficiency ranking. Last year was the all-time best for the CCC era, coming in at 31. This year-to-date we rank 165. Fluctuations are normal and we did bring in Langborg for a more offensive identity this year - a guy the rest of the team ribs about his poor defense. Even with that, the ranking for the Chris Lowery era averages out to 98, versus 130 for CCC's NU years without Lowery. That 130 would be much higher if you take out the other defensive specialist we had for 2 years: Billy Donlan from 2017 to 2019. NU with Donlan averaged a ranking of 76 in defensive efficiency. Donlan is also known as a top tier defensive brain. You may recall that he was at Michigan the prior year when that team came out of nowhere to win the B1G tournament. An article crediting Donlan's defense for that turnaround at the time noted "The Wolverines won the Big Ten tournament, winning four straight games in four days in an improbable run, in no small part, because of their defense."
After Donlan left NU, was CC and staff capable of teaching the same principles without him? Not in the least.
Our average defensive efficiency ranking fell through the floor. After Donlan delivered an average ranking of 76, NU in the subsequent 3 years before Lowery fell to a ranking of 195. From 76 to 195 is a clear indication that these things aren't just learned and maintained on inertia.
All told, if we put those numbers together:
a) the 4 years when we had a defensive specialist on staff, our average defensive efficiency ranking averaged 87
b) The other years CCC was our coach without a defense specialist, we ranked 146.
Finally, as a team I don't think NU can afford to walk away from a clear defensive identity, nor can we really win without a defensive specialist. We have enough challenges in recruiting, and shooting is the kind of thing that goes hot and cold with the best of coaching. Defense on the other hand is more responsive to hard work and smart thinking in how a player uses everything from his eyes to his feet. It's a function of work and intelligence - two things that we have to rely on to remain competitive.
So yeah, Lowery is our Hank. Arguably so was Donlan - but I don't feel Donlan had the old/experienced coach vibes that Lowery has! In either event, there is plenty of evidence that if Lowery leaves we are going to have do more than hope people took notes.