I had this conversation in a baseball thread when the dodgers won like 12 in a row or something silly.....maybe it was more......If I remember right at the time everyone was saying bet the dodgers its a lock then they got swept by the pirates or someone......
For everyone who thinks the under is a lock I would ask you this question.
Your job is to set lines. You study these two teams and you decide the line should be 38.5. that is a good line for these two teams. But you also know this game has gone under 16 years in a row and its one of the easiest trends for joe public to point to. You know every body will be on the under. So you can set the line at 35.5 increase your chance of the over and your still confident more money will come in on the under. If you were a linesmaker knowing this has hit 16 years in a row and the public will bite on that wouldn't you PURPOSELY shade the line lower than it should be.
Now someone could say why didn't they do that after year 10 or year 11 or year 12.......and I would say you know what your right, but to me the more something is OBVIOUS and talked about its accounted for in the number I can promise you that.