Because the samples are too small to move the markets.

You will see more movement as we approach 10 games in..
The stats start to correlate and become more relevant.

Also you may see a little more movement after the window closes when each teams squad can be accurately evaluated.

FWIW these markets are not always very liquid and tie up capital for a long period.(Which has value)
Professional bettors prefer making lots of decisions with small edges.
To turn over the bets quicker.
If your edge is 10% on a season market bet you could make much more with that money turning it over multiple times on 1-5% edge bets.

Posted By: usacanary, Aug 31, 14:07:28