Reposting a post of mine from the thread I linked above about the 1929-30 season.
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This isn't exact, but
this article gives NHL scoring leaders as of December 24, 1929 - one week after the rules were changed. Here are the numbers for all players named in the article. (GP listed are their teams' games played.)
1. Frank Boucher - 14 GP, 9 goals, 15 assists, 24 points
2. Cooney Weiland - 14 GP, 11 goals, 12 assists, 23 points
3. Bill Cook - 14 GP, 22 points
4. Dutch Gainor - 14 GP, 22 points
5. Hec Kilrea - 14 GP, 14 G, 7 A, 21 points
6. Nels Stewart - 15 GP, 17 G, 4 A, 21 points
7. Aurel Joliat - 16 GP, 20 points
8. King Clancy - 14 GP, 19 points
Doing the math, over the rest of the season these players scored:
1. Cooney Weiland - 30 GP, 32 G, 18 A, 50 points
2. Frank Boucher - 28 GP, 17 G, 21 A, 38 points
3. Bill Cook - 30 GP, 37 points
4. Hec Kilrea - 30 GP, 22 G, 15 A, 37 points
5. Nels Stewart - 29 GP, 22 G, 12 A, 34 points
6. Dutch Gainor - 28 GP, 27 points
7. King Clancy - 30 GP, 21 points
8. Aurel Joliat - 26 GP, 11 points
All players who weren't listed here finished with 50 or fewer points on the season, with the exception of Dit Clapper who scored 61.
When you look at the scoring list from the last two-thirds of the season, played entirely with the offside rule in place, Weiland separated himself from the rest of the league in scoring during this time. It appears that the games played without the offside rule had very little to do with Weiland's scoring in this season.
Boucher was leading in scoring right up until the end of February. As of February 18 he had 58 points and Weiland had 52.
Source.
But over the rest of the season Weiland scored 21 points in 9 team games and Boucher scored 4 points in 10 team games. Weiland passed him during the game of Feb 25 when Boston beat Pittsburgh 7-0 and Weiland scored four goals and one assist to reach 61 points to Boucher's 59.
Source.
Boucher missed the last two games of the season with a broken shoulder blade, and Weiland scored three goals against the weakend Rangers in the final game of the season to put a stamp on his record-setting season.
Source.
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Unless I'm missing something, history has misrepresented the role of the no-offside rule in Weiland's scoring title. The rule was only in place for the first 12-15 games or so, and Weiland was in a group of players within two or three points of the scoring lead at that point. Weiland opened up his scoring lead after the offside rule was put in place.
WIth regards to Weiland's voting results, Frank Boucher was leading in scoring for most of the season and Weiland only took the scoring lead in late February. When you consider that awards ballots were submitted in late February to early March at the time, it's very possible that Weiland was not the league leader in scoring when some ballots were submitted.