Don't use a three week sample to make long term determinations. Just because betting against line movement would win you 70% of your wagers in one three week period doesn't mean it wouldn't lose you 70% of your wagers in the next three week period.
I am no expert on line movement. There are a few folks I've gotten to know over the years from this site that really have a strong read on it. Some really trust it as the basis for a majority of their plays, others find it to be folly for wannabe pros. There does seem to be a near consensus among true professional gamblers, however, that understanding line movement is essential to winning long term.
Having said that I am no expert, there are a few things that I have noticed:
-It takes time to understand how to read the differences between "public" and "smart" line movement. Sometimes the line moves because so much money is bet on one side that the book wants a balance, and sometimes the line moves on a much smaller amount of money bet because the book wants to keep future bettors away from a side they like. One tip that fletcher taught me was that on certain favorite line moves, the book is essentially giving away the fact that they are scared to death of public heavily backing a favorite that will win easily. I think Indianapolis on Thanksgiving day was a great example of this.
-Sometimes when a line doesn't move, it is telling you as much as if it were moving. One well respected Mad Jack's member once showed me a list of lines that didn't move a bit. When I checked the results over those several days of scores, I noticed that underdogs hit at a high percentage. He insisted that books were taking one sided action on favorites in those games (as generally happens), but they were more or less betting the underdog themselves by keeping the line static. Obviously a book will almost always go broke eventually if they allow one sided action like that on all games, so you can't just assume that this is the case just because a line doesn't move.
-Pay close attention to Pinnacle, CRIS and Olympic. They are arguably the top three books for taking large action from all comers. You have to spend time watching these bellweather books to understand how they move and what opinions they reveal as they move (or fail to move) lines. Pinnacle, especially, likes to take sides on games. They are very hard to beat because they tempt you with lower vigorish, but in the long run they attract enough losing bets to usually come out ahead if a gambler is playing at multiple outs. For example, they like to do things like offering Lakers -5 -112 (and their opponents +5 +102) while other books are on Lakers -5 1/2 or -6 at -110. These are tough reads because in some cases Pinnacle is just balancing their action to attract Laker bets, but in many cases they are revealing that they want large, "sharp", bettors to bet the Lakers with them because they feel that their opponent is the "right"side.
-Remember that every half point and every bit of vigorish matters. Far too many bettors simply shrug off line movements against them, especially when not on "key" numbers like 3, 4 and 7 in football. Over the long term, it becomes almost impossible to win if you consistently ignore line movements against you. Remember the search is always for value. Even top bettors struggle to top a 55% winning percentage over their lifetimes. When I place a bet on a play that has moved a half point against me, I am losing valuable percentage points off that 55%. Remember that the difference between 55% and 52% (where you are a consistent lose) is not much.
-I will get gruff from my old macroeconomics professor for this, but it is better to err on the side of caution in almost all examples. Opportunity Cost will get you killed in gambling. It is a fine line to walk, because if you pass on too many winners often your confidence will erode, but generally keeping your number of plays to a minimum is best. For instance, last night I lost 200 in Opportunity Cost by passing on the Wiz/Suns under at the last minute. But over time, I will keep my self from going broke by passing rather than playing questionable bets.
-The vast majority of offshore books move "on air". Very, very few books stand firm to their lines even if other books are getting hammered with one-sided action. Most books just deal vanilla odds that are in line with what the rest of the industry is doing. The assertation earlier in this thread that books only move because there is money coming in is simply wrong. All it takes is one day of looking at the Best Bettor screen to figure that out. They will still move if they get pounded on one side, but even then many books are unwilling to post an "opinionated" number for fear that they will get an avalanche of action after a "false" move.
-Remember that the top guys at Pinnacle and Olympic bet lots of money themselves through beards at lesser books. I'd guess that top guys at other books like CRIS do this as well. What this means is that occasionally you will see a bullshit line put out by one of these books early in order to get smaller books to copy them and put up a bad line. Then the beards for the top guys will bet massively on this bad number before quickly changing their number back to where it "should" be. In these cases, you have to act quick, but sometimes you can tail those plays before the value evaporates.
