Rivalry Week: "You can throw out the records when these two teams play."

EyesOfTexas's post regarding the relative lack of upsets in the Texas/Texas A&M series got me to thinking about the line, "You can throw out the records when these two teams play." Any truth to that axiom for other in-state rivalries? Clearly, it is not true for T+1. See the comments I made to EOT on his post:

Thanks to the power of the internet I have found historical betting lines for every game back to 1980 (27 games). In those 27 games, 17 times a team has been favored by greater than a TD — I am arbitrarily using that as my definition of an upset — the favorite has won the game SU 14 times or 82% of the time.

2006 Texas lost 7-12 as a 13.5 point favorite
1984 Texas lost 12-37 as a 11 point favorite
1980 Texas lost 14-24 as a 12.5 point favorite

As an aside, the fact the line has been greater than a TD 17 out of the last 27 meetings is indicative of an unbalanced series. Twice in 27 years has the line been less than 3 points -- 1998 and 1999 were both 2.5 point games so, I would definitely not characterize 1998 as an upset.

I grabbed the other 9 in-state rivalries for the rest of the week and did some analysis:
Note: Those in-state rivalry games were OU/OSU, UNC/DK, UW/WSU, UGA/GT, Clem/SC, FSU/UF, BAMA/AUB, VT/UVA, Miss/Ole Miss.

Of those 243 games (9 series x 27 years), a team was favored by more than 7 points 109 times (44.8% of the time) compared to 63% of the time in the Texas/Texas A&M series. Close games are not expected 40% more often than other rivalry games.

The favorite won that game 90 times or 82.4%, compared with 82.4% in the Texas/Texas A&M series. For comparison, per Phil Steele's database from 1980-2004 (see link below), favorites of greater than 7 points won 82.0%. Interesting.

Angles of note:
The favorites of greater than 7 points in the UGA/GT, FSU/UF, and Clem/SC are a combined 32-2 SU. The Ole Miss/Miss St favorite of greater than 7 is only 3-2 straight up.

Of those 243 games, the line was only less than a FG 40 times or 16.4% and the Ole Miss/Miss St series contributed 11 of those. The Texas/Texas A&M series line was less than 3 only twice in the last 27 years or 7.4%. Close games were expected less than half as often as other in-state rivalries.

The Egg Bowl is clearly the most evenly matched rivalry game since 1980.

Since I know someone is going to ask, here are the numbers for TX/OU. Of the 28 games since 1980, a team was favored by more than 7 points 12 times (42.8% of the time). That favorite was 8-4 SU or 7567%. The line was less than a FG 5 times or 17.9%.

Reference links:
Phil Steele's database from 1980-2004; oddly 2005- current is not available
Historical Betting Lines and Results since 2000

Your thoughts?