The total # of team rebounds pre-1969 seem too high and may be incorrect, implications for possessions/pace?

[WestGOAT]

I was having a look at the total number of rebounds in a season for teams, and in theory the known total rebounds from the gamelogs should more or less (ideally it should be perfect) match the recorded season total.

For example let's have a look at the '70 Lakers:
If you count the total number of rebounds from their RS gamelogs you get: 4132
(https://www.basketball-reference.com/teams/LAL/1970/gamelog/)
Whereas if you look at the total stat team table you get: 4154
(https://www.basketball-reference.com/leagues/NBA_1970.html#totals-team)

Minor difference right?

However, look at the '62 Royals:
total number of rebounds from their RS gamelogs: 4892
(https://www.basketball-reference.com/teams/CIN/1962/gamelog/)
total stat team table: 5665 (!)
This is a difference of 773 , which is 15.8% more than actually found in the gamelogs.
(https://www.basketball-reference.com/leagues/NBA_1962.html#totals-team)

I basically found the same pattern up to the 1969 season:

Code: Select all

   Season Phase Tm_ID Phase  gTRB Ph-TRB           
                          G   sum    tot    Δ     %Δ
0    1960    RS   PHW    75  5244   5916  672  12.81
1    1962    RS   CIN    80  4892   5665  773  15.80
2    1963    RS   SFW    80  4751   5359  608  12.80
3    1964    RS   CIN    80  4830   5400  570  11.80
4    1964    RS   SFW    80  4871   5499  628  12.89
5    1965    RS   PHI    80  4646   5246  600  12.91
6    1965    RS   SFW    80  5042   5715  673  13.35
7    1965    RS   STL    80  4476   5208  732  16.35
8    1966    RS   CIN    80  4979   5559  580  11.65
9    1966    RS   PHI    80  5024   5652  628  12.50
10   1966    RS   SFW    80  5087   5727  640  12.58
11   1967    RS   CHI    81  4544   5295  751  16.53
12   1967    RS   CIN    81  4651   5198  547  11.76
13   1967    RS   SFW    81  5353   5974  621  11.60
14   1968    RS   CIN    82  4504   5129  625  13.88
15   1968    RS   PHI    82  5143   5914  771  14.99
16   1968    RS   SEA    82  4742   5338  596  12.57
17   1968    RS   SFW    82  5320   6029  709  13.33
18   1970    RS   LAL    82  4132   4154   22   0.53
19   1971    RS   SDR    82  4659   4686   27   0.58
20   1972    RS   LAL    82  4598   4628   30   0.65
21   1976    RS   SEA    82  3693   3715   22   0.60
22   1977    RS   SAS    82  3684   3660   24   0.65
23   1978    RS   WSB    82  4141   4164   23   0.56
24   1980    RS   SAS    82  3644   3668   24   0.66

Now I am not actually sure how bball-ref calculates team pace pre-1974:
https://www.sports-reference.com/blog/2013/12/estimating-pace-and-per-possession-ratings-1951-1973/

But if total team rebounds are being used, this could actually lead to pace being over-estimated then right? And if that's the case actually ORtg/DRtg are being under-estimated and over-estimated, respectively. I wouldn't know by much though, and in the end if it matters much, but something to keep in mind when thinking about how much stats were really "inflated" in the '60s to due relatively high pace.

[Sportemind]

I haven't look into to it too much, but potentially the issue is team rebounds? If you look at the first couple of box scores, the total rebounds for the team is just the sum of all the individuals' rebounds. They do not include team rebounds - which are times when no one successfully possesses the ball after a shot (e.g. the ball going out-of-bounds).

But I'm not sure. I also don't know if team rebounds were a thing 50 years ago.

[TrueLAfan]

You're both correct. The NBA counted team rebounds--where possession changes without an individual getting credit for a rebound--as part of total team rebounds until 1969. Those types of rebounds mean that listed team totals are about 11-13% higher prior to 1969.

The best way of seeing this is to to what you did and add up the totals for individual players and compare it to the team total. For instance, the players on the 1967 Lakers were credited with a total of 4811 rebounds. The "official" total of 5411 includes team rebounds--a 12% jump. Any attempt to do any statistical analysis involving rebounding prior to 1969 will have to take this into account.

[batmana]

I haven't look into to it too much, but potentially the issue is team rebounds? If you look at the first couple of box scores, the total rebounds for the team is just the sum of all the individuals' rebounds. They do not include team rebounds - which are times when no one successfully possesses the ball after a shot (e.g. the ball going out-of-bounds).

But I'm not sure. I also don't know if team rebounds were a thing 50 years ago.

Team rebounds were definitely a thing as early as the 50s or 60s. In fact, I read players shooting FTs and missing the 1st one were given an individual rebound as well in between FTs which explains Russell's and Chamberlain's astronomical rebound numbers. Since OP found such a big disparity, I guess team rebounds where the ball goes out of bounds were either not counted as individual rebounds to any player, or that practice changed at some point (?). Even though I don't have a link currently, I'm sure I've read it many times that team rebounds (as the scenario I described) were also counted as individual rebounds. Considering Russell and Chamberlain particularly not being too good free-throw shooters, and considering 3 FTs to make 2 existed, they probably collected a pretty significant number of "team rebounds" to their individual rebounds numbers.