Never mind that Pettitte lost the perfect game on a Hairston fielding error with two outs in the seventh, or that he eventually lost the no-hitter and shutout in a 5-1 Yankees win. What’s really important (and alarming) is that the final piece of Camden’s once-ruckus home-field advantage is in jeopardy of being swept away.

Attendance numbers at the jewel on Eutaw Street have slowly been disintegrating since the Birds drew 3.7 million fans in 1997 (also their last playoff appearance). Last season, the O’s failed to hit the two million-fan mark for the first time since 1988.

Wednesday matinee games against the Rays have been host to sparse crowds for a few years. That’s to be expected when you haven’t had a winning record since Bill Clinton was president. But Monday night, as Pettitte was mowing through the Baltimore lineup, Camden Yards felt like Yankee Stadium South. Pettitte missed on one particular two-strike pitch and a disappointing “ooooohhhhh” rippled through the park.

Wow.

This would never happen in Boston. Eight years ago (before the Red Sox snapped “The Curse”), Mike Mussina was one out away from a perfect game at Fenway until a Carl Everett single saved Beantown from going into cardiac arrest. At no time was the crowd decidedly backing Mussina. Nor should it have been.

But this isn’t Fenway circa 2001. This is Birdland in the midst of a 12-year postseason drought. And in a drought like this, the last thing to go is the fan base. Only winning will bring it back. Baltimore is loaded with young prospects and they can’t develop soon enough. The Orioles were the first franchise to draw one million (1954), two million (1983) and three million (1992) people in a season, but after Monday night, that feels like ancient history.