How much has Mike Piazza been struggling? With two out in the bottom of the ninth yesterday, the Brewers opted to pitch to him with the tying run on third base and Robin Ventura on deck.

Even the guy who made the decision thought it was a little crazy.

“I guarantee you, half of the people in the park thought I was nuts,” Milwaukee manager Davey Lopes said after the Mets’ dramatic 4-1 win in 10 innings at Shea.

“I’m sure they couldn’t believe I was pitching to Piazza and if he got a hit, I would have been killed.”

But yesterday was not a day for Piazza to play the hero. He left that to Jay Payton and Ventura.

Now the Mets embark on a significant road trip with their star catcher mired in a 2-for-18 slump, coming off a four-strikeout game.

Not to worry, though, Mets fans. Piazza has figured out the problem.

“I just basically [stink],” said Piazza with a laugh after his average dipped to .329. “There’s not much to it. I have to keep going back out there. I hope I hit bottom today. I know I can’t get any worse. Actually, I don’t want to say that. It’s a long year.”

Yesterday probably seemed like a year for the catcher. It was the second time in his career that he whiffed four times in a game. The only other time came in 1994 against Montreal.

“Jeff Fassero did it,” Piazza said. “But I don’t like to think about that.”

He won’t want to remember much about this one, either. Piazza struck out against Brewer starter Jeff D’Amico in the first with Lenny Harris on third base, and again in the third with runners on first and second. He also fanned in the sixth, and made the second out in the critical ninth, when Lopes had closer Curtis Leskanic face Piazza rather than walk him.

To Piazza, it wasn’t such a high-risk proposition.

“You really start pressing when you go through something like this,” Piazza said. “This game can be very frustrating at times. You try to avoid thinking about stuff like that, but maybe in the back of your mind it’s there.”

In all, he left four runners on base – three in scoring position.

But the day wasn’t a total loss for the backstop. He did guide Mike Hampton through eight innings without allowing an earned run.

“It means a lot to me when Mike comes over to me and tells me I did a great job behind the plate,” Piazza said. “When I’m not hitting the ball, at least I can do a little bit. I know that much. I felt like I contributed to the win today, however little.”

Hampton thought Piazza was owed that much respect.

“This is a humbling game,” Hampton said. “Even the best – and he’s definitely the best – have bad days. He’s our leader. He’s going to turn it around.”

And he’ll make some manager look like a fool for pitching to him.