Tuesday, May 06, 2008

Historical stats on ESPN

I was watching SportsCenter on ESPN last night. After showing the Hornets and Pistons go up 2 games to 0 in their respective series, they showed the number of times the home team that were up 2-0 won the series in 4, 5, 6 and 7 games...as well as the number of times the home team lost the series.

How meaningful are these numbers when it comes to the Hornets and Pistorns? Without any other information about the teams or other valuation numbers, I think they are pretty good. But we do have more information.

The Detroit Pistons were 6.5- and 6-point favorites in their games against the Orlando Magic.
The Hornets were 3-point favorites in each of their games against the San Antonio Spurs.

Assuming a 4-point home court advantage in the playoffs, and a zigzag effect of one point for game 3 when down 2-0 going back home, that would make the lines for game 3 about:

Orlando -2.5 Detroit
San Antonio -6 New Orleans

These quick estimates may be off a little bit, but they should be pretty close. San Antonio will be a bigger favorite than Orlando in game 3 and probably in game 4 as well. And if there is a game 5 or other future games, San Antonio will probably have a higher chance to win each of their games than Orlando. So San Antonio has a higher chance of winning their series than Orlando.

There wasn't any need to use point spreads to make that judgement. This is probably obvious to any NBA fan. But this should also be obvious even if you don't know a single player on either team. And that makes the historical stats that ESPN shows not very meaningful.