I understand your point however, I think it’s been more talent related as of late..I think you are going to find that issue was never talent related... it was scheme and technique... it showed up coinciding with our defensive gurus overhauling the line scheme that had been in place since the blitztburgh days, to one where the DLinemen weren't eating blocks and gaps and were " stopping the run on the way to the QB"
And sometimes it was more about the want to, than the talent, especially when you’re talking about playing physical run defense..
And I have on many occasions, watched the lack of effort and “want to” from our run stoppers in the middle of the defense lately..