The O/U are not always equal when the betting odds are factored in. Here they are for all SEC games and which include the odds –
https://www.saturdaydownsouth.com/sec-football/bovada-releases-updated-2017-sec-overunder-win-totals/
For MIZ – 6.5 is the O/U, with the Over 6.5 at +120 and the Under 6.5 at -150. The odds show you are betting $100 to win $120 on the over, and betting $150 to win $100 on the under.
In addition to just the number, look at the odds to find the value in a bet. I think that there may be some value in the Bama under 10.5 because it is paying $160 for every $100 bet, and you’re laying a good amount of cash on the over at $200 to win $100. At 10.5 and an OOC against FSU with the SEC West schedule, two losses could be possible. Again, not necessarily that I think they will lose two games, but I think there could be some value in the under bet because of the odds on the payout.