All it takes is a "few" large wagers on the Yanks...compared to a million "mediocre" wagers on the Sox and the line would still move this way....or it's a mind game being played on you by the books, or they may already have huge action on Yankees to win series and people are hedging....or...or...or....you get the point. Don't overanalyze.....this game in my opinion is a toss up. Once again, could argue for both sides easily. Just throw some lunch money on it if you absolutely have to have money on the game....
Good luck