It's always hard to analyze April attendance, which can be greatly affected by weather and other factors. According to this study, Opening Day attendance was down less than 1 percent from last year, which isn't bad considering the ongoing economic woes.

But there are some ominous signs already around MLB.

On Wednesday, two teams experienced the smallest crowd in their ballpark's history -- 10,071 at Progressive Field in Cleveland, which opened as Jacobs Field in 1994; and 10,610 at Rogers Centre (formerly Skydome) in Toronto (you can see the empty seats in Toronto in the picture above, which shows ex-Mariner Brandon Morrow on the mound against the White Sox). That's on top of the 9,129 at Camden Yards on Monday, the smallest crowd in the 19-year existence of that marvelous ballpark.

Those three examples show just how tenuous a team's hold on a community can be. The Blue Jays, Orioles and Indians all went through stretches -- long stretches -- where they absolutely owned their towns, and their games were the toughest tickets in baseball.

The Blue Jays drew more than 4 million fans in three straight seasons, (1991-93, during which, not coincidentally, they won two World Series). Only three other teams in history have drawn 4 million fans -- the Yankees (four times, 2005-2008), the Rockies (who set the all-time mark of 4,483,350 in their inaugural season of 1993, playing at Mile High Stadium), and the Mets (2008, their final season at Shea).

From 1992 to 2000, the Orioles played to sellouts virtually every night, averaging more than 40,000 fans per game, peaking with 3.71 million in 1997 -- when they made it to the American League Championship Series.

And the Indians, during their run of great teams in the 1990s, which led to two World Series appearances, set a major-league record with 455 consecutive sellouts from June 12, 1995 to April 4, 2001.

Those days are now distant memories, as all three teams have seen their attendance plummet as their performance on the field has done the same. The Orioles have had 12 straight losing seasons and are off to a 1-8 start. The Indians have had their share of success in recent years, including coming within a win of the World Series in 2007, but they are coming off 97 losses last year; while the Blue Jays haven't been to the playoffs since 1993 and find themselves perpetually in arrears of the Yankees and Red Sox.

The Mariners have had a similar downward trend in attendance, though not so dramatically. As was the case with the Blue Jays, Orioles and Indians, they had the magic combination in the early 2000s -- a wonderful new stadium and a winning team. That led to huge attendance numbers -- more than 3 million fans for four straight years (2000-03). But from a peak of 3.54 million in 2002 (an average of 43,710 fans a night!), the M's have been in slow but steady decline, down to 2,196,461 last year. That's a drop of 16,000 fans a night over the course of seven seasons. Not at all coincidentally, the Mariners finished last in four of those seasons.

How well the Mariners draw this year will be largely dependent, ultimately, on how they perform. Last year's attendance was the lowest number since Safeco opened in the middle of the 1999 season. Excitement over the team's moves was high in the offseason, but excitement can quickly turn to disillusionment if the team struggles.

I always find it interesting and instructive to see how big the dropoff is from the home opener, invariably close to a sellout, to the second day of the home schedule. In their glory days, the Mariners' dropoff used to be fewer than 10,000. In 2002, coming off a 116-win season, the M's drew 40,831 for Game 2, a decline of only 5,205 from Opening Day. This season, however, their decline was 27,833, the biggest drop since Safeco Field opened (but just barely; last year's Day 2 dropoff was 27,439). Here's a chart, listing first the attendance for the home opener, then for Game 2, and then the decline, for each full season at Safeco Field:

2010

Monday, vs. A's: 45,876 (L)
Tuesday,: 18,043
Decline: 27,833

2009

Tuesday, vs. Angels: 45,958 (W)
Wednesday: 18,519
Decline: 27,439

2008

Monday, vs. Rangers: 46,337 (W)
Tuesday: 25,204:
Decline: 21,133

2007

Monday, vs. A's: 46,002 (W)
Tuesday: 25,292
Decline: 20,710

2006

Monday, vs. Angels: 45,509 (L)
Tuesday: 20,051
Decline: 25,458

2005

Monday, vs. Twins: 46,252 (W)
Tuesday: 28,373
Decline: 17,879

2004

Tuesday vs. Angels: 46,142 (L)
Wednsday: 37,947
Decline: 8,195

2003

Tuesday vs. Angels: 45,931 (W)
Wednesday: 35,492
Decline: 10,439

2002

Monday vs. White Sox: 46,036 (L)
Tuesday: 40,831
Decline: 5,205

2001

Monday vs. A's: 45,911 (W)
Tuesday: 27,226
Decline: 18,685

2000

Tuesday vs. Red Sox: 45,554 (L)
Wednesday: 29,243
Decline: 16,311