I'm going to offer the following data as it seems to show an interesting relationship between how the Maple Leafs perform in the NHL and how the Blue Jays do in terms of attendance.
Code:
Jays Jays Maple Leafs
Year Record Per Gm Playoff run
-----------------------------------
1977 54-107 21,263 2nd
1978 59-102 19,291 3rd
1979 53-109 17,675 2nd
1980 67-95 17,288 1st
1981 37-69 14,247 1st
1982 78-84 15,753 missed
1983 89-73 23,832 1st
1984 89-73 26,049 missed
1985 99-62 30,862 missed
1986 86-76 30,315 2nd
1987 96-66 34,302 2nd
1988 87-75 32,039 1st
1989 89-73 41,678 missed
1990 86-76 47,966 1st
1991 91-71 49,402 missed
1992 96-66 49,732 missed
1993 95-67 50,098 3rd
1994 55-60 49,287 3rd
1995 56-88 39,257 1st
1996 74-88 31,600 1st
1997 76-86 31,967 missed
1998 88-74 30,300 missed
1999 84-78 26,709 3rd
2000 83-79 21,058 2nd
2001 80-82 23,359 2nd
2002 78-84 20,221 3rd
2003 86-76 22,216 1st
2004 67-94 23,457 2nd
2005 80-82 24,876 no season
2006 87-75 28,422 missed
2007 83-79 29,144 missed
2008 86-76 29,627 missed
It seems perhaps the Jays were helped in that at the same time the Jays were doing well (late 1980s and early 1990s) the Maple Leafs were doing poorly. From 1989-92, the Leafs missed the Stanley Cup playoffs three times and were bounced in the first round the other time.
Notice how the Jays' attendance drops by 20% in 1995, and drops again in 1996 at the same time the Leafs were in their fourth consecutive season of making the playoffs. In the spring of 1997 and 1998, the Leafs miss the playoffs and the Jays' attendance stays relatively stable.
But look at the big drops in Jays attendance in 1999 and 2000, in spite of decent records. Those drops coincide with the realignment of the NHL which saw the Leafs go into the same division as Ottawa, Montreal, and Boston, and the Leafs making it to the 3rd round in the spring of 1999 (the Leafs were eliminated on May 31). The five seasons of 2000-04 which saw the Leafs making playoff runs saw the Jays' attendance remaining steady in the 22,000 range.
The 2004/05 NHL season was cancelled, so no Stanley Cup playoffs in the spring of 2005, and for the next three seasons after that the Leafs miss the playoffs, which at the same time sees the Blue Jays per game attendance figure rise nicely.
Now, of course, correlation is not causation, but the numbers are interesting nonetheless.