This part bothered me and didn't seem right, but I couldn't put my finger on it. But then I figured why:
what you're saying here isn't wrong, but here's why it feels odd - even when teams play twice in a season, they very nearly almost NEVER play at each other's home fields. They play at one team's home field and then at a neutral site: CCG or bowl game.
So within a season, at least, there isn't a 6-8 point swing.
I meant in terms of the difference between my place and your place. Ie, if my Buckeyes and your Gators are considered "exactly equal" then, in theory, UF would be favored by about 3-4 points in the Swamp while tOSU would be favored by about 3-4 points in the Shoe. Thus, the 6-8 point swing.
But you are right, in almost all cases when teams play twice in a season the second game is at a neutral site so it is only a 3-4 point swing. However, if we get home field for the first round of the expanded 8-team playoff then I think we'll see some two game sets at each other's fields and/or at the same team's field twice.
Using the examples I posted above for 8-team CFP fields:
2014: No rematches in the first round. There are two potential rematches. #1 seed Bama beat #7 seed MissSt in Tuscaloosa and could meet them again if both made the CG. #5 seed Baylor beat #6 seed TCU in Baylor and could meet them again if both made the CG.
2015: #3 seed MSU played both #5 seed Iowa (B1GCG) and #7 seed tOSU (in Columbus) and could meet tOSU in the second round and/or Iowa in the CG.
2016: #4 seed PSU beat #5 seed tOSU in Happy Valley and the rematch would be in Happy Valley in the first round of the playoffs. Both of them already played #6 seed Michigan so the winner could also have a rematch in the CG.
2017: #4 seed tOSU and #6 seed UW played in the B1GCG and would rematch if both made the CG.
2018: No potential rematches.
2019: #1 seed LSU and #5 seed UGA played in the SECCG and could rematch in the second round.