I'm a little wary of people when they say, "Bet on one team when such and such situation exists," because I know that the value of any wager is basically a function of the value in a number. So "systems," as such, should be utilized but not necessarily followed religiously. After all, if a system dictates that the favorite rates a play, there is a certain point at which the line is high enough so as to take any value away from a play.
What I like to do in basketball is at least be on the lookout for certain situations, so that there is the possibility of a value play if the spread is in line with what the relative power ratings of the two teams are.
These are some of the "situations" I look out for:
Win & Travel -- A team wins straight-up, whether it is at home or on the road, and then travels to play somewhere else the next day. Travel in the NBA is such that teams have to travel early, and the schedule becomes so arduous that it has a tendency to take a toll on players and teams. Plus, when we go through the winter months there are often weather situations that create delays. If you're lucky, you'll get an early word on a team that may have been delayed at an airport that prevented them from reaching their ultimate destination. It can happen even in the case of chartered or private flights. That means they get to the hotel late, which sometimes means they are dragging ass on the court the next night. This situation becomes worth even a further look when the opponent has had a night off coming into the game.
There is a specific "Situation within a situation" that I like to watch out for. It's when a team that played the night before has to go into a place like Utah or Denver, in an instance where the Jazz or Nuggets have had at least a day of rest coming into the game. The reason I say it is that these are high altitude places, where the visiting team could be gasping for air in the second half, and that tends to play to the advantage of a home team that is used to that kind of thin air.
Fourth Game in Five Nights -- Once again, we're operating on the same principle. Remember one theme that runs through much of this analysis - in the NBA, teams do not go all out every night. It is simply impossible to keep up that kind of pace, in the same way it is not possible for a baseball team to be on an emotional "high" for 162 games in a season. In the hoops world, this is even more pronounced, since the sport itself is much more physically demanding.
When a team is playing its fourth game in five nights, or even its third game in four nights, or if I can look ahead to a schedule that includes that kind of itinerary, I want to take note of it, because somewhere in there is going to be an effort that is somewhat less than honest (I don't mean in the corrupt sense, of course). Once again, though. it's not something that is necessarily uniform, because as I recall, during the strike year a while back there were scheduling quirks where, because games had to be made up during a short period of time, teams sometimes played three nights in a row. What was happening as we looked was that they were not lethargic in the third game (indeed, if you bet against those teams you would have been behind), but more often let up a little in the second game, as apparently they were saving up energy for the third.
Payback -- In the NBA, it's often a bitch. A team goes out on the road and gets beaten badly. Then, in the return match, on their own home court (and this is particularly the case with teams from different conferences, because they only play twice a season), the team beaten the first time puts forth a special effort. I'm certainly looking for these kinds of "revenge" situations, and obviously, the line and the relative strength of the two teams has to play into it.
Look-aheads -- These can always present an opportunity, and they are very real. Let's say a team like the Celtics or Lakers are playing a team the caliber of the Kings or the Nets one night, and then they have to travel to play one of the NBA's top teams, like the Spurs or the Cavs, the next night, whether that's at home or on the road. Players are human and they "get up" for those games against top opponents, even if it is in the regular season. They are often on national television to boot. They also know they often have to do little more than lace up their shoes to score a win over one of the "have-nots." So they may rest a lot of players when they have a big lead, looking to conserve the energy of their stars and allowing for a "backdoor" cover at the same time, Watch for opponents in these situations who have a certain degree of three-point efficiency, because that is exactly what they are going to do. Understand a couple of things here - one is that there is a tremendous disparity these days, as it has been for some time, between the top and bottom teams in the NBA, and also, because of that disparity, some teams have so much depth that their second unit can outplay the other team's first unit. A bench could actually extend a lead, so you have to look at which teams may have the ability to do that.
Those are just a few basics to get you started Betiing on the NBA!