Kevin
I can't say for sure but there are a couple of reasons I can think of that may have affected the HoF.
1. Shortly after the update there were a number of races where the end of race processing was carried out multiple times. The side effects of this were drivers/staff contracts expiring even though before the race they had more than 3 races remaining, multiple sponsor awards, multiple wages paid etc. Of course, this also meant multiple rep points were awarded. If you did well and your race was affected by the multiple parsing you would have received a lot of Rep.
2. During the update the rookie tier was removed. This resulted in Pro tiers and some Elite tiers becoming more populated. Because the rep calculation is influenced by the number of players in a tier, people who were dominant in a league were instantly receiving more rep points for winning a race than they were before the update.
There may be other reasons I haven't considered.
These reasons are probably correct. But one thing i find very, very odd is that after the update, the 40-60 rep lead I had in my nation was immediately gone after 2 days, and now I'm somehow 166 behind. I have had the experience of climbing down due to very bad results back then and I didn't even drop off this much.