FINALITY GETS its moment of tribute in a quick nod and a pause, and then both Don Mattingly and Buck Showalter move on to the heat of the moment. This weekend - Sunday to be precise - Showalter writes Mattingly into his home lineup card for the last time. Most likely. End of an era.

"Yeah, I've thought about it," Mattingly said, and then refused to dwell on what he thought. Was it the last time he'd walk into Yankee Stadium? Was it the last time he'd put on those pinstripes? "Oh," he said and shrugged away the end of his thought.

"I've thought about it," Showalter said. They were minor-league Yankees at Nashville in 1981, one on the way to creating a New York era and the other at the point where his talent for thinking was greater than his talent for playing.

Now Showalter makes the daily decision on whether Mattingly plays, on whether the numbers that appear in the papers every day are to be taken at face value. Deciding whether the revered old star can still play is always fraught with peril. "Donnie is going to be the first baseman until the season ends," Showalter said last night. In his view, there is much more to Mattingly than meets the eye.

"No question, he's the heart and soul of this ball club," the manager said. It was more than a pledge of allegiance.

Tonight, at 8 o'clock on ESPN - in a taped interview with Roy Firestone - Mattingly says what he wants to say with the intonation and emphasis he wants. Last night he insisted the tone of bitterness that emerged from dialogue released by ESPN was misinterpreted. He's said a number of things this long and painful season that he says he shouldn't have said or were misinterpreted.

These 13 seasons in New York he said were "a movie, not just a picture." Sure there were some bad times, but they fade. And then he said the end should have come with "respect," with "class" face to face. "They don't have to go out and backstab me."

Showalter, in turn, says "[Mattingly's] been part of the reason we're where we are, having a chance at this."

This has been the Mattingly Era of the Yankees, emerging from the Winfield Era. Taken across his time here, Mattingly has been the best and most popular player in New York. It has not been the best era in New York baseball, but Mattingly was the most popular player, his wisdom questioned at times, but never his effort. Now, with his skill eroded by injury, the public question all season has been whether he could be the anchor of their success or the weight that drags them down.

"He is our best option," Showalter said, "I consider everything - for us to win the championship." Some of what he considers is past performance. "I don't deny a player like him or Wade Boggs a chance to do things again. Would it be a surprise to me to see him as a big part of a championship here? No it wouldn't."

Mattingly's production numbers are more appropriate for a shortstop than a first baseman, and interest in Mo Vaughn - who may or may not be a free agent after the next labor agreement - has been a fact of life. "I know the numbers I've put up are not the best," Mattingly said. "I know in my heart I could put up better."

He concedes he knows he's not going to swing the bat like Vaughn or Rafael Palmiero. "At one point I was like Vaughn and Palmiero," he said. "I'm not that way now. Everybody is going to have it happen. I haven't been there for three or four years."

Then he found the irony of being criticized for not hitting enough home runs any more "funny." That was his word. "I've never been a home-run hitter except four years in my life. I never thought of myself that way, even in the minor leagues." The trouble with averaging 30 home runs for four seasons is that all of a sudden people expect you to do it again, and you get paid accordingly. And once he learned how to hit home runs and hit for average, his back broke down and he couldn't hit home runs. Now George Steinbrenner weighs what this Mattingly is worth.

Showalter has his own evaluation. "Everybody in this clubhouse, me and the coaches included, knows what he means to the club," he said. "There's a certain passion and feeling we have when Donnie is on the field. There's an energized feeling, whether he's making a fielding play or driving in a run like he did [the winning run, Monday night]. I'm into numbers as much as anybody, but I try not to let it override my gut feeling and mental and emotional factors in play. He'll take that 0-for-4 or 1-for-5 if he has to. He's willing to do that. He'll tell the right thing to the pitcher; he'll talk to the second baseman, tell people to be aware of something."

The best lineup is not always the one with the best numbers. Showalter credits Mattingly at first base for Andy Pettitte, the rookie, having picked off more runners than any pitcher in the league. "He's the reason why the infielders don't have a lot more errors. We're second in the league in defense. That makes the pitchers better." The manager's voice was rising in tone and increasing in speed.

"He's playing with some restrictions; he's had a lot of experience playing with it. He's one of the most unselfish players I've been around. He's the rare athlete who checks his ego at the door. I can bat him ninth or first. He's somebody who's happy after he's 0-for-4, if we win. He won't even think about it until the next day when he tries to make adjustments."

That's strong tribute. And at this point there is no one better to play at the position. Mattingly went into last night's game hitting .353 over 10 games. After three limp at-bats in a game they needed to win, he followed Ruben Sierra's game-tying homer with a hard double - pulling an outside pitch because that's what the situation demanded - setting up the two runs that won the game. He still can do some things right. He has eight games to play. Then what?

Does the pain mean he doesn't want to play any more? Does the irritation mean he doesn't want to play for Steinbrenner any more? He knows he doesn't want to hang around for 20 at-bats as a pinch-hitter at any price.

He says he won't decide until he gets away from the day-to-day of the race, of thinking who the next day's pitcher is going to be and what the other teams are doing. "My heart will tell me the answer," he said. What he really would like is be the old Donnie, again. But it can't be.

He knows from having watched the demeaning of Winfield and Goose Gossage that it doesn't happen that way here. Perhaps, he thought it would be better for him. Foolish thought.

"I don't want to do anything but play baseball now," he said. "Is this going to be your last day of working for the company?" he said to the questioners. "Is it the last day you're coming to cover at Yankee Stadium?"

The thought keeps getting pushed away. He says he has no trouble focusing. "I can still play," he said. "I love to play. Some days I don't." Showalter lets his heart tell him, too. Steve Jacobson

Copyright 1995, Newsday Inc.