I was wondering why the Bills were over too.
After looking at some numbers I'm pretty sure I found it.
Last year's rollover was $1.3M BUT there was a -$6M adjustment. That adjustment is now -$2M.
The huge adjustment was thought to be from Von Miller's sack bonus, but whatever the reason it's down to only -$2M.
That's the $4M added difference you are looking for @No_Matter_What.
Spotrac shows the adjustment numbers but unfortunately OTC doesn't show its work, somehow, they had the right adjustment and Spotrac just
caught up.
https://www.spotrac.com/nfl/buffalo-bills/cap/