It was the sort of evening Seattle Mariners fans once were able to envision only in their daydreams.

Outfield flags rippled in the wind. Stadium light banks, juxtaposed against the blue sky, rekindled memories of a childhood delight: the two-block walk to the ballpark, 30 minutes before the first pitch, for a baseball game at night. Mowed grass patterns, symmetrically etched, offered still more evidence that there’s no turf like real turf.

The Mariners, home to face Baltimore after a three-city, cross-country road trip that found them winning five of nine against the toughest competition in the sport, were in the thick of a division race midway through a turnaround season.

All this going on Monday night, and a Safeco Field crowd of 24,018 showed up.

Fewer fans were on hand to watch a winning team than were on hand for a corresponding Monday home date last season. On June 30, 2008, a Seattle crowd of 30,192 watched the Mariners – 31-50 and hopelessly headed for oblivion after 81 games – take on Toronto.

For that matter, fewer fans came to see the Mariners on Monday than came to see the final Monday night game at the Kingdome, the functional but ultimately flawed concrete structure that had deprived fans the joy of experiencing big-league baseball in the great outdoors.

This Saturday, the Mariners will celebrate the 10-year anniversary of the opening of Safeco Field. The ballpark is as gorgeous now as it was then, and global warming patterns responsible for some crazy winters in the Pacific Northwest have done nothing to undermine Seattle’s pleasant summer climate.

So what gives? Why are fans so reluctant to embrace a capable team that, win or lose, almost always finds a way to pack suspense into the late innings?

To borrow a White House staff slogan popularized during the Clinton administration, it’s the economy, stupid. Major League Baseball executives were braced for an attendance drop related to the recession – and they’ve gotten it, though the fall-off hasn’t been as severe as feared. Still, for the typical family, entertainment dollars are at a premium.

I’ve got another theory: Mariners fans are in limbo. They’re still tuned in, they’ve still got their eyes on the ball, but the prevailing uncertainty – should they be sellers before the July 31 trading deadline, or should they be buyers? – is forcing them into a wait-and-see mode.

It’s nobody’s fault, either. General manager Jack Zduriencik can’t be criticized for failing to identify what course he’ll take over the next three weeks.

Zduriencik would be foolish to proclaim the Mariners as one-big-bat-from-the-playoffs buyers, only to trade off those few prospects who are thriving on the farm in pursuit of a chase that turns out to be a lost cause on Aug. 1.

On the other hand, Zduriencik would be just as foolish to give up hope on a team that woke up on Tuesday only 31/2 games behind the first-place Angels.

The reaction to a bombshell trade designed to improve the future makeup of the roster would overshadow every savvy move Zduriencik has made since replacing Bill Bavasi.

If Zduriencik can’t be blamed for sitting still, the fans can’t be blamed for sitting at home. How do you invest emotion in players – even likable players who execute on the field and have achieved camaraderie off of it – when you’re not certain they’ll be wearing the same uniform next year, or next month?

Glancing at my scorebook from Monday night, I see only three starting players virtually assured of returning in 2010: Ichiro Suzuki in right field, Franklin Guttierez in center, and Jose Lopez at second base, or third base, or wherever. But that’s it. Three players, and I wouldn’t be shocked if Lopez is dealt over the winter.

Otherwise, first baseman Russell Branyan is a potential free agent who’ll attract attention at the deadline. Chris Woodward (third base), Ronnie Cedeño (shortstop), Rob Johnson (catcher) and Ryan Langerhans (left field) are fill-ins, and Ken Griffey Jr. (designated hitter) is halfway through his last waltz as homecoming king.

Which brings us to Monday night’s starting pitcher, Jarrod Washburn. His undefined status has made him Seattle’s hottest sports talk-show topic, with the possible exception of Tuesday night’s starting pitcher, Erik Bedard.

Retiring 27 of 28 Orioles hitters on Monday, Washburn’s performance was the most efficient ever delivered by a Mariners pitcher in Safeco Field. Afterward, instead of reveling in the once-in-a-decade gem, fans took wind sprints into four different camps: Trade him now; trade him at the deadline; keep him for the rest of the season and then and let him go as a free agent; and immediately work on signing him to a contract extension.

Given the fractious state of the fandom in 2009, it’s no wonder that Safeco Field has attracted crowds in excess of 40,000 only for the opener and two games against the Red Sox. Eleven other games have drawn crowds of at least 30,000. Through the first week of July last year, the Mariners already had 24 crowds of more than 30,000.

Because the organization doesn’t pay me to recruit warm bodies for vacant seats, I’ll never tell Joseph Everyday Fan how to spend his money. Besides, I understand the hesitance to fall in love with a team whose players may not be capable of a long-term relationship.

But after a terrific road trip, after winning 21 of 34 and climbing back into contention, the tepid box-office reception nevertheless was a jolt: The Mariners returned to a house that was half-empty.

Then again, an optimist would note that it was half-full.

john.mcgrath@thenewstribune.com