Goaltender Bill Durnan (born 1916, Toronto) played from age 25-27 for the Montreal Royals in the old Quebec Senior Hockey League. Through his early/mid-20s, he'd been in (presumably) moderate obscurity in Kirkland Lake, though he did win the Allan Cup there.
Then, suddenly -- and for reasons I don't understand -- Durnan was promoted to starting goalie of the Montreal Canadiens in 1943, aged 27, having never played in the NHL before. (This 1943-44 season was also Maurice Richard's breakout season.)
Durnan didn't exactly struggle. He played all but 10 of Montreal's 210 games over the next four years, led the League in wins every season, led the League in GAA every season, and thus was 1st-team All Star and Vezina winner each of his first four seasons. In the '44 and '46 playoffs combined, he went 16-2 and had the best GAA both springs, winning two Cups. (He also had the best GAA in '47, but the Habs lost in the Final.)
Has any goalie EVER had a better first four NHL seasons?
He was 1st-team All Star and Vezina winner again his last two seasons ('49 and '50) and then abruptly retired, apparently because he couldn't handle the stress of NHL hockey.
I get that his early peak was in a war-weakened NHL, but it's a heck of a first four seasons...