I can share more of the data behind this but what I did is I compared the Home and Away records of the 11 Big11Ten teams (membership from when PSU joined until UNL joined) against each other only. I looked at 1993-2023. I started with 1993 because that was Penn State's first year in the league and stopped with 2023 because Stassen hasn't updated to include 2024 yet. Here is the summary:

So I guess those Pink Visitor locker rooms really do work, eh?
Most of this makes sense to me but there are some outliers that, for now, I've just chalked up to randomness. If you look at the five teams with the least HFA, two of them are two of the worst three overall (#10 IL and #9 MN) and another two are two of the best three overall (#1 tOSU and #3 UW). That makes sense. Illinois and Minnesota are usually bad enough that they are going to lose most of their games regardless of location. Conversely, Ohio State and Wisconsin are usually good enough that they are going to win most of their games regardless of location.
On the other end of the spectrum, four of the six teams with the biggest HFA are among the "middle five" overall (#5 IA, #4 PSU, #6 MSU, #8 PU).
The outliers and my theories on why they are:
As the #2 team in the league, Michigan shouldn't have that much HFA. I think they do because they didn't get to be a distant #2 (much closer to UW than tOSU) by being consistently a distant #2. Instead they got there by being a REALLY close #2 for part of the time and well below #2 the other part. My theory is that they got a lot of HFA help when they were well below #2 and more in the middle of the league where HFA matters the most.
As the worst team in the league, Indiana shouldn't have much HFA at all. I really can't explain why theirs is second highest. Maybe part of it, at least as compared to IL and NU is that I think IU has been more consistent than those teams. Without deeply researching it, it 'feels like' NU and IL have been a bit more Jekyll and Hyde with league championship highs and just flat awful most of the rest of the time whereas IU has been consistently a bit better than IL's and NU's lows but without the top-end. I don't know.
As the #7 team in the league, Northwester aught to have pretty strong HFA but theirs is even les than Ohio State's. This is probably because of the Jekyll and Hyde nature of their performance (see previous paragraph).