“The Stanley Cup is the toughest championship to win in team sports” was cited in print in 1993. The Stanley Cup (hockey’s championship trophy series) is said to be more difficult than the Super Bowl (football), World Series (baseball), and the NBA championship for a number of reasons. A hockey team must win 16 games (four wins each in four series) to win the Stanley Cup, but an NFL team could win the Super Bowl by winning just three games. An NHL division leader does not receive a first-round bye.
 
“The Stanley Cup tournament is the most difficult to win professional sports” was cited in 1996. “It is acknowledged by athletes from all sports that the Cup is the hardest championship to win among the team sports” was cited in 1999.
 
   
Wikipedia: Stanley Cup
The Stanley Cup (French: La Coupe Stanley) is the championship trophy awarded annually to the National Hockey League (NHL) playoff winner after the conclusion of the Stanley Cup Finals. Originally commissioned in 1892 as the Dominion Hockey Challenge Cup, the trophy is named for Lord Stanley of Preston, then–Governor General of Canada, who awarded it to Canada’s top-ranking amateur ice hockey club, which the entire Stanley family supported, with the sons and daughters playing and promoting the game. The first Cup was awarded in 1893 to Montreal HC. In 1915, the two professional ice hockey organizations, the National Hockey Association (NHA) and the Pacific Coast Hockey Association (PCHA), reached a gentlemen’s agreement in which their respective champions would face each other annually for the Stanley Cup. After a series of league mergers and folds, it was established as the de facto championship trophy of the NHL in 1926 and then the de jure NHL championship prize in 1947.
 
Google News Archive
17 April 1993, Pittsburgh (PA) Post-Gazette, pg. C-6, col. 1:
Difference of opinion
Sorry, Andy, winning Stanley Cup is sports’ greatest feat
JOHN STEIGERWALD
(...)
The Stanley Cup is the toughest championship to win in team sports.
 
Google News Archive
27 May 1996, The Blade (Toledo, OH), “You never know with beat up Red Wings” by John Gugger, pg. 25, col. 1:
As certain as 24 hours in a day and the sun sets the west, the Stanley Cup tournament is the most difficult to win professional sports.
   
Google Books   
99: My Life in Pictures
By Wayne Gretzky with John Davidson
Kingston, NY: Total Sports Pub.
1999
Pg. 8:
It is acknowledged by athletes from all sports that the Cup is the hardest championship to win among the team sports.
 
Google Groups: alt.sports.hockey.nhl.buffalo-sabres
League is full of it
Magnet
6/20/99
(...)
The Stanley Cup is the most difficult trophy to win in all sports.
 
Google Groups: alt.sports.hockey.nhl.vanc-canucks
Sweet-ass article.
Dennis Prouse
6/19/01
Thank you, Shanny—it was an amazing article.  When they say that the Stanley Cup is the toughest trophy in sports to win, THIS is what they are talking about.
 
Google Groups: alt.sports.baseball.sf-giants
What do barry Bonds, Tiger Woods, Michael Jordan, and Wayne Gretzky have in common??
Joe Macias
10/29/02
FYI: Wayne Gretzky is White, and he’d rather have 1 Stanley Cup ring than a dozen World Series Rings.
 
The Stanley Cup is the toughest trophy to win in all sports…
 
Google Books
How to Succeed in the Game of Life:
34 Interviews with the World’s Greatest Coaches
By Christian Klemash
Kansas City, MO: Andrews McMeel Pub.
2006
Pg. 181:
“I’ve been involved in this business now for eighteen years as a coach and I know the Stanley Cup is the toughest thing to win.”
 
Bleacher Report—San Jose Sharks
Lord Stanley’s Cup: Hardest Trophy to Win in Professional Sport
By Andy Bensch , Senior Writer Dec 2, 2008
(...)
The Stanley Cup is without a doubt the hardest championship trophy to win in all of professional sports.
 
Harder than winning the Superbowl, harder the winning the World Series, and harder than winning the NBA Title.
(...)
The team that wins the Stanley Cup will have won their league title despite only having a 7% chance at winning the tournament, will have played more play-off games then required by most other sports, have endured more physical pain than any other sport, for a longer period of time, and will have done so using less money than any other professional sport.
 
Google Books
My First Goal:
50 Players and the Goal That Marked the Beginning of Their NHL Career
By Mike Brophy
Plattsburgh, NY: McClelland & Stewart Ltd.
Pg. 189:
Some people say the Stanley Cup is the hardest trophy to win in all of professional sports, and there’s no doubt in my mind that it is.
 
NBC Sports
STANLEY CUP ‘TOUGHEST THING TO WIN IN SPORTS’
It’s takes 16 playoff wins - and eight weeks of self-induced pain - to lift the legendary silver chalice
April 29, 2011, 3:04 am
Bob Duff
 
Twitter
VictorSAURUS Seymour
‏@vjseymour
@NHLonNBCSports would luv to see it in person. The OLDEST Trophy in ALL of Sports and the Hardest,Toughest to WIN. Lord Stanley Cup The Best
12:26 PM - 15 Apr 2015