MINNEAPOLIS, JULY 4 -- For a couple of years, the Minnesota Twins had been telling the people here that the rebuilding era was over. These Twins, they said, needed only fine-tuning.

They had developed a steady everyday lineup that had put a young superstar in center field (Kirby Puckett), an all-star at first (Kent Hrbek) and a 34-homer man at third (Gary Gaetti). They traded for starting pitching, getting Mike Smithson from Texas and Bert Blyleven from Cleveland.

So for the past two years, the one and only goal has been finding a big-time reliever; and when last season ended, the Twins believed that more strongly than ever.

The Twins had blown 26 leads in the seventh, eighth and ninth innings and, had they saved just half of those, their disappointing 71-91 finish would have been 84-77 and put them in contention for a division championship.

Enter Jeff Reardon.

"I knew how much people were counting on me," he said, "and that didn't bother me. The only thing is that people should know one man can't do it all. I had some good years in Montreal, and we never won. But I was excited about it and even more excited when I got to spring training and saw what a good team this was. I couldn't believe I'd never really heard of the Twins that much because we have some outstanding players."

Fast forward to the morning of the Fourth of July, and the '87 Twins have just slipped percentage points behind the Kansas City Royals after holding onto first place for three weeks. They're doing it with a combination of things. Puckett is putting up MVP-type numbers. Hrbek is on a 40-homer, 100-RBI pace, and Gaetti is on a 30-homer, 100-RBI pace. The starting rotation has been passable, just good enough to get by.

What's different about these Twins is that Reardon, a 31-year-old former University of Massachusetts history student, is the main man in a bullpen that is now one of the best in the league.

He was the Twins' biggest acquisition over the winter -- coming in a deal with the Expos for pitcher Neal Heaton and three minor leaguers. The Twins also picked up reliever Juan Berenguer, who had been released by the San Francisco Giants, for the bargain-basement price of $152,500.

Together, Berenguer and Reardon were 10-4 with a 3.91 ERA, 18 saves and 127 strikeouts in 117 innings before last night's 4-1 win over Baltimore. And in that game, Berenguer pitched two innings of scoreless relief to pick up his third save.

The acquisition of Berenguer and Reardon has allowed Keith Atherton, last year's stopper, to go back to a middle-inning role, where he is more comfortable.

Reardon's 16 saves are six more than Atherton's team-leading 10 last year; and as a team the Twins have 23, one fewer than all last season.

"Having them gives us a completely different feeling," said Puckett (.349, 14 homers, 50 RBI). "It makes all the difference in the world. It has gotten discouraging the last couple of years when you'd take a lead into the late innings and watch it get away. You couldn't help but think about it, but my feeling always was, 'Well, it can't happen again.' You have to admire Reardon. He comes in with power stuff, goes right after people."

Twins Manager Tom Kelly said, "I think having Jeff has helped our offense. We lacked so much confidence in the late innings last year that we not only didn't think we'd win, we didn't score many runs either. Our whole game became defensive. Now, we go into the eighth and ninth thinking we're going to win, and those have been some of our best offensive innings."

They make a perfect odd-couple combination and the biggest hopes for a team that hasn't finished above .500 since 1979. Reardon is outgoing and personable, a loose guy on a very loose team. Berenguer is quiet, almost sullen, doesn't speak to reporters and isn't especially outgoing with teammates.

What they have in common is their right arms. Both have 90-mph fastballs, and both have tight, sharp curveballs that can freeze a hitter in his tracks.

"Jeff has been every bit as good as we expected," Kelly said, "and Berenguer has been terrific. He's having an all-star first half. He's got to be at least considered for it."

There have been some low moments, too. Reardon has blown seven saves, including one for Mike Smithson Friday against Baltimore. He did end up getting the victory with three shutout innings, but only after allowing two inherited runners to score and tie the game in the ninth.

He has also had a problem with home runs, having allowed 10 in 41 1/3 innings, including three grand slams.

"You've got to look at the situations he comes into," Twins pitcher Frank Viola said. "Nobody's perfect, but he's done a helluva job. He always comes out with that fire."

After five seasons and 146 saves in Montreal, Reardon said he was glad to get back to the United States. He hasn't always agreed with the Twins' tender handling of him, especially in spring training when they didn't allow him to face American League teams, thus hoping the advantage would be with him when the season began.

"It's been a little tough," he said. "I'd spent eight years in the other league {three with the New York Mets} and knew those hitters pretty well. I haven't known a lot of the guys over here, and have had to rely on help from the other pitchers. I'd never even followed the American League that much, but as I see the teams a second time, things should be easier."

But while he says "one man can't do it all," he seems to have assumed the responsibility that one man should. He takes bad performances "very hard," said one teammate. "He really gets down on himself."

The Orioles saw that side of him Friday when he thought home plate umpire Dan Morrison had squeezed the strike zone on a couple of pitches. At one point, Reardon took two steps toward the mound and screamed "something you can't print" at Morrison.

"I lost control," Reardon said, "but other than that, I'm not going to say anything about the umpiring. I do take it hard, but the role of the short reliever has a lot of pressure. When I come into a game, my feeling is that I have to strike out every guy I face. When I fail, it stays with me a while. I don't go home and beat up my wife, but I don't just forget about it, either."

The Twins say they admire this in him. "He's a bulldog," Kelly said.