It is simply based on observation and knowing various defenses through the years.....I have always felt like I can tell when it is emphasized, and when it is not. It was obvious to me when Leavitt was here that it was a major point of emphasis, and the opposite when Eliot arrived. Further, I have a few friends that are DC's in college, and they have reiterated to me....they have to work this EVERY day, or else they can tell that their guys regress in this aspect consistently.
Catching isn't so much of a change at the nose, it was done a lot last year as well....and I didn't really understand it then either. But the difference is that our NG (Tuopo) would play with better leverage, would line up much tighter to the line of scrimmage in 2016 so as to not allow the OL to get a full head of steam (these are kind of one in the same to me, because often when a DL is so far off the ball, his first instinct is to stand up to see what is happening, creating a position of bad leverage), and our 3 and 5 techniques definitely played more up field.