some sportsbooks are slower than others adjusting their lines and if players continually beat that number from a result of steam they take exception in some cases...this is also in conjunction with a players profile and history and that particular sportsbook also.
A "steam move" is the phrase used to describe the line change when a large amount of money goes down on one side of a game in a short period of time. This is usually due to the wise guys making a move on a particular side. After these players choose their side, the bookmakers usually act accordingly by moving their number in an attempt to make the other side look more attractive to other bettors.