In this article, we'll look at the concept of Differential From Opponent Averages and how it can be factored into handicapping the NBA. From a logical standpoint, the Differential From Opponent Averages, or DOA, should work better in the professional leagues than they do in college football or basketball for the sole reason that the pro leagues can be considered "closed" leagues, meaning teams will not play anybody from outside their league. In college sports, even the powerhouse teams occasionally play a game against a Division IAA or Division II team, and those teams may in turn have played games against Division III schools or even community colleges, which can distort AOPR rankings a bit, but there's no such worry in professional sports, where the majority of handicappers don't even factor in any sort of strength of schedule factors into mathematical systems.
Looking at the concept of DOA and
how it relates to the NBA, we'll look at the lone game on the schedule
Thursday, Feb. 12, 2015 that saw the Cleveland Cavaliers visiting the Chicago
Bulls. The Cavaliers went off as 2.5-point favorites and the total on the game
was 199.5.
The Cavaliers came into the game
averaging 102.2 points per game and allowing 99.1, while the Bulls averaged 102
points and also allowed 99.1 points per game. On the road, Cleveland is
averaging 100.5 points per game and giving up 101.1, while the Bulls score
103.6 and allow 101 when playing in front of the home fans.
Cleveland's 102.2 points per game
where scored against teams that allow an average of 99.9 points per game, which
would give the Cavs a +2.3 on offense. Cleveland's 99.1 points per game allowed
came against opponents which score an average of 99.4 points per game, so the
Cavs get a +.3 on defense.
For the Bulls, their 102 points a
game came against teams that allow an average of 100 points per game, giving
Chicago a +2 on offense, while their 99.1 points allowed per game came against
teams that scored an average of 99.8 points per game, giving Chicago a +.7 on
defense.
If we were to add up both teams,
we'd have Chicago favored by .1 points and we could give the Bulls 3 points for
being at home and come up with a rough line of Chicago -3.1 points. Since both
teams have played more than 40 games, we can also look at each team's home and
away averages and then bypass the automatic three-point home court allotment.
Using that method, Cleveland's 100.5
points per game would net them a +.6 on offense and their defensive average of
101.1 points per game would yield a -1.7 on defense, giving the Cavs a road
rating of -1.1. For Chicago, their home offensive average of 103.6 would give
them an offensive rating of +3.6, while their defensive average of allowing 101
points per game would give them a -1.2 on defense for an overall rating of
+2.4. Added to Cleveland's road rating of -1.1, we'd have the Bulls as
3.5-point favorites.
The one other area we can look it is
totals and for that, the one additional piece of
information that we need is the median points scored per game and that happens
to be 200 even, which makes for an easy starting point. When using the DOA
premise for totals, a plus on offense will be added to your starting point, as
the teams are better than the average on offense, while the a plus on defense
will be subtracted for the reason that the team performs better than average
defensively, which should lead to a reduction in scoring.
By the same token, a minus on
offense will see a reduction from your starting figure, while a minus on
defense will lead to an addition, as the team is worse than average on defense,
which should lead to an increase in scoring.
If we look at the total from an
overall basis, we'd have our starting figure of 200 plus Cleveland's +2.3 on
offense and then subtract Cleveland's .3 on defense, giving us 202. Chicago
gets a +2 on offense and -.7 on defense, so we'd have a figure of 203.7.
If we were to use home vs. away
numbers, which is ideal for totals, as some teams do play much differently at
home or away, we'd have 200 plus Cleveland's .6 on offense and add the Cavs
+1.7 for their minus on defense, giving us 202.3. We then add Chicago's home
offensive rating of +3.6 and then add their minus 1.2 for home defense, giving
us a projection of 207.1.
Remember, this is just one way of
looking at a game, but it does have some merit to it and it never hurts to look
at all of the different factors that you possibly can when handicapping.
