George Hainsworth had a long and successful 13 season professional career. It's not so well known that he played senior amateur hockey for 10 seasons before he turned pro, and he may deserve some additional credit for his amateur play.
First off, the NHL website, hockeydb, and hockey-reference list him as having been born in 1895. But wikipedia gives his year of birth as 1893. Per Find a Grave, his gravestone displays 1893-1950. Articles published at his 1936 retirement gave his age as 43, consistent with the 1893 birth. I'm inclined to believe the 1893 date of birth and I'm curious to know why it's listed as 1895.
If 1893 is correct for his year of birth, Hainsworth played junior hockey in Berlin (soon to be renamed Kitchener) until 1912-13. He got into some senior games that year, and played senior hockey for the next 10 years, until 1922-23. The junior/senior transition makes sense with an 1893 date of birth, as he would have played his last junior season at age 19 and played senior full time from age 20 to 29.
Then he played with Saskatoon of the WCHL at ages 30-32, for the Canadiens from age 33-39, and for the Leafs from ages 40-42. Hainsworth retired at 43 in November 1936 after a handful of games in 1936-37, when Conn Smythe released him, saying Turk Broda was just as good and 20 years younger. He then played 4 games for the Canadiens in December of 1936 when Wilf Cude was injured, before retiring for good. One columnist said Hainsworth had half a dozen minor pro offers but was financially secure and had determined to retire when he was done with the National Hockey League.
I have very little information about Hainsworth's play in senior amateur hockey from 1913-1917. Hainsworth was the goalie for the Kitchener Greenshirts when they won the Allan Cup in 1918. Kitchener played a smothering back-checking team game in the final win over Winnipeg Ypres. I'm not sure what Hainsworth's all-star record in the OHA was,
but if Doc Stewart's unsourced wikipedia page is correct, Stewart may have had the better all-star record in the OHA, with a first team all star in 1919, 1922, 1923, and 1924, and a second team all star in 1918.
I think the OHA had a very high level of play in the late teens and early 20s, and certainly included some pro quality players. OHA teams won the Allan Cup in 6 of 7 years from 1917 to 1923, only interrupted by the Winnipeg Falcons in 1920. And Southern Ontario players weren't very represented in pro hockey in the 1910s, but then poured into pro hockey in the mid 1920s after American expansion and big money.
Take Hainsworth's final OHA season for an example, 1922-23. I don't have the final standings, but going into the final week, Hainsworth's Kitchener Greenshirts, the Hamilton Tigers, and the Toronto Granites were all tied atop the standings with 8-3 records. Then Hamilton beat Kitchener in the semi-finals before losing to the Toronto Granites in the final. The Granites went on to win the 1923 Allan Cup and to represent Canada in the 1924 Olympics.
Who were the players for those Kitchener, Hamilton, and Toronto clubs?
1922-23 Kitchener
Goal: Hainsworth
Defense: Merrick, Hemphill
Centre: Hiller
Wings: Hillman, Schnarr
Subs: Soloman, Shirk
I believe only Hainsworth and Werner Schnarr made the NHL from this group, and Schnarr only played one season with the Bruins. Hainsworth, Hiller, Soloman, and Shirk had all been on the 1918 Kitchener championship team.
1922-23 Hamilton Tigers
Goal: Charles “Doc” Stewart. Played 10 seasons in OHA senior and 3 for the Boston Bruins. Was the OHA first team all star for this season.
Defense: Hap Day, Jimmy Herbert, Day played 14 NHL seasons and Herbert played 7 NHL seasons.
Centre: John Brackenborough. Played 7 NHL games with the Bruins, likely could have had a longer NHL career if he hadn't lost an eye on the ice in 1923.
Wings: Carson Cooper, Herb Mitchell. Cooper played 8 NHL seasons and was twice top-3 in goals and points. Herb Mitchell played two seasons for the Boston Bruins.
Every single Hamilton starter went on to play in the NHL, most for the Boston Bruins. When Boston finished over 0.500 in the 1925-26 season, 60% of their goals were scored by the Cooper and Herbert forward duo, and Doc Stewart was their goaltender.
1922-23 Toronto Granites
Goal: Jack Cameron. Was offered a contract by Canadiens but he turned it down and went into business.
Defense: Dunc Munro, Beattie Ramsay. Munro played in 8 NHL seasons and was voted a first team all star by the coaches in 1926-27. Ramsay took a year off from his coaching career to play in one NHL season.
Centre: Hooley Smith, had a Hall of Fame NHL career
Wings: Harry Watson, Bert McCaffrey. McCaffrey played 7 NHL seasons. Watson turned down NHL offers and went into business, and is considered one of the best amateur players to never turn pro.
Every Toronto Granites starter went on to play in the NHL, except for Watson and Cameron who turned down NHL offers. Smith had an outstanding Hall of Fame career, and Munro had a great start before he got distracted by his off-ice activities.
Based on those rosters above, it's likely that Hainsworth was often not playing with the best roster during his time in the OHA, at least after 1918.
Did other top NHL goalies of Hainsworth's era have substantial senior amateur or minor league
performances worth considering? I would suggest the following.
Lorne Chabot for his two seasons winning the Allan Cup for Port Arthur.
Roy Worters for his two seasons winning the USAHA championship with Pittsburgh.
Maybe
Tiny Thompson for his championship in the AHA.
All of these seasons were at ages 23, 24, or 25, meaning they weren't just out of juniors. Other than that, the best goalies generally made the NHL in their early 20s and I don't think their pre-NHL careers really add anything.