Josh Hader isn’t even old enough to legally drink the champagne that was being splashed around the Quad-Cities River Bandits dressing room Saturday night.

He was more than happy just to wear some of it.

A little more than six weeks after being traded from his hometown Baltimore Orioles to the Houston Astros organization, Hader helped put the finishing touches on the River Bandits’ second championship season in three years.

The slender 19-year-old left-hander shut out the South Bend Silver Hawks on three little singles through seven innings as the Bandits completed a sweep of the Midwest League championship series with a 4-2 victory in front of a lively crowd of 3,607 at Modern Woodmen Park.

Hader, who went 2-0 in just five appearances with the Bandits in the regular season, also went 2-0 in the postseason and he was never in any sort of serious trouble Saturday. He allowed only four baserunners, only one of whom got as far as second base. He also struck out eight Silver Hawks.

Mitchell Lambson fanned two more hitters in retiring South Bend in the eighth inning. Closer Andrew Walter, who had been virtually untouchable in the playoffs, served up a two-run home run to Rudy Flores on an 0-2 pitch in the ninth, but then got the last two outs to preserve the win.

Hader said he was not nervous at all in the biggest starting assignment of his young life.

“Not in the beginning,’’ he told reporters amid the on-field celebration following the game. “Now I’m starting to feel a little bit of the excitement.

“I knew we had a great team,’’ he added. “The chemistry on this team was great. I had a feeling that we were going to take it.’’

Two years ago, the Bandits rolled through the playoffs without losing a game. This time they suffered just one setback, in Game 2 of the Western Division finals with Beloit.

“No doubt about it, we were playing our best baseball right now,’’ said shortstop Carlos Correa, who struck out three times Saturday but still batted .333 in the playoffs. “We were doing everything right. It paid off and we’re champions.’’

A big part of the title drive was the work of the pitching staff, which went above and beyond most people’s expectations. In eight playoff games, the Q-C staff had an earned-run average of 2.15 with just 50 hits allowed in 71 innings.

“I was expecting great pitching but I wasn’t expecting consistency,’’ manager Omar Lopez admitted. “That’s what we got was consistently great pitching every night.’’

The strong mound work was crucial in Saturday’s Game 3 of the best-of-five finals as the Quad-Cities offense didn’t do much after the first two innings.

The Bandits jumped in front by scoring two runs in the first inning with the help of an error. Tony Kemp dropped a bloop single down the left-field line to start the inning and when Teoscar Hernandez tried to bunt him over, South Bend pitcher Aaron Blair threw the ball into right field. Kemp scored from first and Hernandez raced to third. He scored one hitter later when Danry Vasquez rifled a ground ball into right field.

Rio Ruiz added to the lead by driving the first pitch of the second inning over the left-field fence for his third post-season home run. The lead reached 4-0 later in the inning when Jordan Scott, who had singled, scored from first on a double by Kemp.

The offense took most of the rest of the night off. In fact, the Bandits struck out two or more times in the third, fourth, fifth and sixth innings.

But with the way Hader was slinging the ball, it didn’t matter.

“The pitching staff did a great job,’’ Correa said. “The defense was there, too. It was a team effort. We put it all together and now we’re the champions of the Midwest League.’’

Lopez had a simple explanation for the late-season surge of his team, which included 20 victories in the last 24 games.

“I think these guys just enjoyed winning and that’s why they won,’’ he said.

The manager was as euphoric as anyone as everyone jumped around in jubilation after it was over.

“Those guys behind me did it all year,’’ he said, pointing to his players. “It’s just an amazing, unforgettable moment. They deserve it.''