Seven things about No. 7, Joe Mauer

Joe Mauer enters the National Baseball Hall of Fame on Sunday, elected on the first ballot five years after his retirement. The Twins have retired his No. 7, so here are seven memorable moments in his career:

The Metrodome wasn’t just the home of the Twins. It served as an indoor venue for college and high school baseball games, many occurring during the evenings following Twins’ day games. One such game took place involving Joe Mauer’s Cretin-Derham Hall team during his senior season.

“Now we get to see what this Joe Mauer guy is all about,” one pressbox denizen — me — said while crafting a Twins game story for the next day’s edition.

It didn’t take long to see what all the hype was about. Mauer blasted a home run to right field over the baggie in right field in his first at bat, the sound reverberating throughout the nearly empty Dome.

He finished the game with a cycle. By the end of his high school career, Mauer struck out just once in four years and batted .625 his senior season. The Twins selected him with the first overall pick of the 2001 draft — and never regretted it.

The Twins were so sure Mauer was ready for the majors that they traded A.J. Pierzynski, a former All-Star catcher, to San Francisco after the 2003 season and named Mauer the starting catcher for 2004. And he had not played above Class AA yet. It saved the club a few bucks as well.

“We all knew he’d be replacing me someday and he always handled the situation with a lot of class,” Pierzynski said before leaving for his new team.

Cheers turned into groans during the next game as Mauer tore his left meniscus when his cleats got caught in the artificial turf while chasing a foul ball. He missed 49 games.

While the Detroit Tigers were accusing the Twins of manipulating the air inside the Dome to their advantage, the Twins celebrated Mauer’s first major league home run.

It came later than anticipated, as Mauer had missed nearly two months of games following knee surgery. But he recovered in time to rejoin the Twins on June 2. He was 0-for-9 since his return before stepping in to face Detroit’s Esteban Yan with two on and two out in the eighth inning.

Mauer got ahead 3-1 in the count but then showed off his advanced hitting approach. A young player normally is geared up for a fastball in that situation, so Yan threw a splitter. The pitch was up in the zone, and Mauer crushed it 408 feet to right-center field for a three-run homer that helped the Twins win 6-5.

Future Hall of Famer Jack Morris was in the Twins radio booth that game for the call with play-by-play announcer John Gordon.

You practiced what you preached, Joe.

Mauer missed more than 350 games during his career due to various injuries. So he had a lot of experience in returning with a bang. And there was no bigger bang than in 2009.

A inflamed sacroiliac joint during spring training cost him the first month of the regular season. He underwent treatment, got some swings in at the Twins complex in Fort Myers, Fla., then played in five games for Class A Fort Myers before joining the Twins for a May 1 game against Kansas City at the Metrodome.

No one knew what to expect from Mauer. Except Mauer. “I always expect a lot,” he said upon his return. “Whatever I can do.”

First at-bat: Home run to left on his first swing against righthander Sidney Ponson.

Third at-bat: Walk. Scores on Morneau’s home run.

Mauer had announced his return with authority. It was the start of a journey that landed him the AL MVP award and a third batting title.

They both were lefthanded hitters. They both were among the best at their positions. They both won AL MVP awards. They even lived together in St. Paul in 2006. You might remember that year. Justin Morneau won the MVP, Joe Mauer led the league in hitting and the Twins played out of their minds the final four months of the regular season.

Mauer met Morneau when he was 18 and the slugging Canadian was 20. Soon, a bromance was born. They worked out together, hit together and became inseparable. The Twins have been blessed through the years with great 1-2 punches. There was Kirby and Herbie, Tony O. and Rodney, Killer and Bob Allison. The M&M boys are right with them. Each of those other pairings includes at least one Hall of Famer.

Best friends in baseball. Unfortunately for the Twins, they played in only one playoff series together, in 2006, because of injuries.

Another thing Mauer and Morneau had in common: Both suffered career-altering concussions. Morneau’s occurred in 2010, Mauer’s in 2013.

On Aug. 19, 2013, during a makeup game against the Mets, Ike Davis fouled a pitch that got Mauer right in the mask. He felt fine on the flight to Detroit, but he began experiencing symptoms during pregame work and was scratched from the lineup. He was placed on the injured list, but his case proved to be more severe. He never played again that season. He battled symptoms during the offseason. His twin daughters were 6 months old at the time, and he had to leave the room if one began to cry.

There was a risk of a worse outcome if he took another blow to the mask. So he was moved to first base, where the Twins had an opening, having traded Morneau. That’s where Mauer played the final five seasons of his career.

Mauer batted .323 with an .873 OPS in ten seasons as predominantly a catcher. He hit .278 with a .746 OPS his final five seasons. His head injury sent his career down a path no one wanted to see. But he was able to walk away from the game without another occurrence.

Mauer played the 2018 season — the final year of his eight-year, $184 million contract signed before the Twins’ move to Target Field in 2010 — without announcing his future plans. But those became clearer on Sept. 30 during the season finale against the White Sox. Family, friends and former teammates were on hand for the game, with many watching from a Target Field suite.

Mauer who started the game at first base, grounded out in his first two trips to the plate then flew out in the fifth. In the seventh, he delivered a clean hit to left field, then hustled out a double, pounding his hands together as he slid in safely.

He made one more appearance at the plate in the ninth — as a catcher. He slipped on the tools of ignorance one last time and walked toward home plate as an announced crowd of 30,114 provided a thunderous ovation while Aerosmith’s “Back in the Saddle” played over the sound system.

Mauer caught one pitch from Matt Belisle as Chicago’s Yoán Moncada, following a pregame agreement, kept the bat on his shoulder. An emotional Mauer waved to the crowd, then took himself and his catching gear off the field for the last time.