When both teams are playing in their first game of the year, my data shows:
1993 to 2003, average betting total 195.4, average actual total 192.0.
Overs against the total: 49-87, 36%
That's a pretty darn good rate for the Under, right?
But...
2004 to 2007, average betting total 192.6, average actual total 194.3.
Overs against the total: 28-20 58.3%
The actual totals are about the same in the two time periods (192 vs 194.3), but the average betting total is drastically different (195.4 versus 192.6).
Digging further to look at the average totals for all games:
1993-2003: average betting total 193.0, average actual total 193.4. Overs ATS went 50.2%
2004-2007: average betting total: 195.9, average actual total: 196.4 Overs ATS went 50.3%
From 1993-2003, the average betting total for the first games of the year were 2.4 points higher than the average betting total for the year. But the average actual total was 2 points lower.
From 2004-2007, the average betting total for the first games of the year were more than 3 points lower than the average betting total for the year...and the average actual total was also 3 points lower.
From this data, it seems to me books mispriced the total too high previously, but have since gotten smart and adjusted the opening totals lower. The opportunity is gone. Anyone betting on the angle blindly with ATS numbers from the previous 14 years or even 10 years are making a fundamental mistake of not realizing the possibility the market has corrected and lines are now more efficient than they were in the past. The conclusion is that the angle is no longer a positive EV play.
If you aren't convinced yet to pass on the Unders based on this angle, here's another look at the three games tonight compared with totals from the last year when they last played (excluding playoff games)
CLE vs BOS. Tonight's total is 180. Looks like they last played on 2/27/2008. The total was 191.5
LAL vs POR. Tonight's total is 196. Looks like they last played on 2/26/2008. The total was 202.
MIL vs CHI. Tonight's total is 195. Looks like they last played on 3/29/2008. The total was 207.5
Personnel changes on teams, coaches change, so I'm not saying these are the same teams. But there is probably not that big of a difference in the team rosters (Garnett and Pierce still on the Celtics, Kobe still with the Lakers, Lebron still with Cavs, etc. etc.).
So, the conclusion is that if you hear/read anyone make a pick on the Under in any of the opening games based on this angle, you know they are making a fundemental mistake. Don't make the same mistake.
