"We do not want a single man who is fit for some form of military service to be allowed to play hockey. But let's have the rejects, or average players, to fill the ranks until the boys come home from marching." -
NHL came close to shutting down during World War II
This sentiment seems to have applied to the goaltenders that the NHL was forced to use, who outside of the guy in Montreal's net, seem to be mostly average rejects:
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No Brimsek. No Broda. Johnny Mowers wins the 1943 Vezina and Stanley Cup, and is off to the Air Force in 44 and 45. While New York's Ken McAuley could be described as an AHLer, he never acually played pro hockey again after 1945, so I don't know if that works. The Montreal Canadiens had the good fortune of being the only team who found a goaltending improvement in Bill Durnan (who I'm sure you must think is Hasek-calibre?)
As for the elite scorers not taking advantage, short answer is they were almost all gone, but A) playing Montreal gave Richard the biggest advantage and the lowest quality of competition, B) Richard was probably the most dynamic goal-scorer the NHL had seen to that point and more capable of pressing his bigger advantage.
That being said, many top guys missed 1945 and had Richard been drafted you might not have guessed that the Rocket would have led the NHL in goals that year by a wide margin.
How didn't Bentley take advantage? He outscored the entire league, including Richard in 1944, before missing 1945. He torched the AHL-calibre teams with 37 goals in 40 games.
Playmaker Bill Cowley had the three best goal scoring finishes of his career in 43, 44, and 45, after scoring 4 goals in 28 games in 1942.
Sweeney Schriner unretired to score 22 goals in 26 games in 1945.
Bryan Hextall missed 1945, but his Rangers were severely depleted before that, (and didn't have the luxury of shooting on the Rangers) after a dropping from first place to last place from 1942 to 1943. Same goes for Lynn Patrick . A 42 year old Frank Boucher called himself back from retirement and scored 4 goals in 15 games.
Roy Conacher missed all of 43-45.
After a Top 10 finish in 1943, Gaye Stewart missed 44 and 45, before returning to lead the league in goals in 1946.
In 1943 Busher Jackson returned to the Top 20 at age 32, after a two year absence from the Top 40.
The day they left in 1942, Woody Dumart and Milt Schmidt were in the Top 10 goal scorers, and Bobby Bauer was 1 goal back. Each man was a Top 10 goal scorer before, and would be after returning to the NHL. However the Kraut Line missed all of 1943, 44, and 45.
Syl Apps scored 23 goals in 29 games and was 1 goal back of the league lead in 1943 before he was injured. Apps then missed 1944 and 1945.
Gordie Drillon finished in the Top 3 in goals for the first time in 5 years in 1943, then stopped playing hockey due to the war.