By Tim Dahlberg,AP Sports Columnist

The year was 1973 and drugs in baseball had an entirely different meaning when the late Tug McGraw rallied both a team and a city by telling them “You Gotta Believe.”

The New York Mets and their fans believed enough to get to the World Series that year.

Times change, of course, and since baseball is always in the market for a catchy new slogan, here’s one for 2005:

“Who You Gonna Believe?”

Let’s begin by checking names off a list that’s dwindling faster than this season’s major league home run totals.

At the top is Rafael Palmeiro, who may have been juiced up even as he poked his finger in the air for emphasis while telling Congress that he never took steroids. Palmeiro seemed convincing then, but he wasn’t on Monday when he proclaimed his innocence, then danced around the ugly details.

Stop here if you haven’t seen this before. The player’s defense is always the same: I didn’t know.

Palmeiro left us guessing as to what sent up the flag, but it’s a safe bet it wasn’t the Jell-O salad on the buffet line at the neighborhood Golden Corral or a bad box of Juicy Fruits.

So, who you gonna believe?

How about Jason Giambi, who admits to being sorry – but won’t say what he’s sorry for. Maybe if he didn’t have a memory lapse when it comes to the most important stuff, his whole act would be easier to believe.

Then again, after Giambi hit 14 homers in July – the most by a Yankee in a single month since Mickey Mantle in July of 1961 – maybe it’s time to do a few more unannounced tests in the New York clubhouse.

Let’s move along to the National League, where Barry Bonds plays for the San Francisco Giants. At least he used to play for the Giants, who had to log onto the league’s Web site this week to find out their star player isn’t likely to return this season.

Bonds is making $20 million this year, but in an apparent effort to keep his cell phone bill down didn’t bother to phone the Giants and let them know he wasn’t going to be around.

Like Palmeiro, Bonds swears he doesn’t use steroids. Surely it’s a coincidence that his personal trainer and longtime friend faces prison time after pleading guilty to distributing steroids, and that Bonds is taking the season off just as baseball starts its first meaningful testing program.

So, who you gonna believe?

How about Mark McGwire? No, wait, he won’t answer questions because the past is the past and, well – that’s in the past.

How’s that campaign to keep kids away from performance enhancing drugs going anyway, Mark?

Sammy Sosa? Of course he wouldn’t dream of bulking up with something illegal, just like he wouldn’t dream of corking his bat. Never mind that this is the same Sammy Sosa who stopped hitting home runs about the same time baseball started testing for performance enhancing drugs.

So, who you gonna believe?

Bud Selig and Donald Fehr?

Selig, you might remember, is the guy who tried to tell Congress that baseball didn’t have a steroids problem, only to later pull a grandstand play and propose a 50-game ban instead of the current 10-days penalty. Fehr is the guy who said he would take that proposal to the players and hasn’t been heard from since.

You have to be slightly suspicious that both might have been involved in the interesting timing surrounding the announcement Monday that Palmeiro tested positive for steroids.

Given the way baseball’s ponderous grievance process works, there’s no doubt those in the know have known for weeks, if not months, about the positive test. The only question is whether it goes all the way back to spring training, when tests were going on about the same time Congress was holding hearings.

There’s no reason to ruin a celebration, though. So Palmeiro was allowed his last untainted moment in the sun a couple of weeks ago when he stroked his 3,000th career hit in Seattle, knowing what was coming all the while.

So, who you gonna believe?

The way things are now, it’s hard to believe anyone at all.