I’m not a sports columnist, but everyone seems to have an opinion about whether Seattle Mariners’ legend Ken Griffey Jr. should hang it up or hang on for one final season.

The case for retirement is pretty straightforward. The man we used to call “The Kid” is flirting with 40, well past his prime, and this year averaged less than one hit every four and a half times he went to the plate. The power hitter who slammed more than 40 homers in seven seasons hit only 19 this year. He used to be one of the fastest players on the team, but now would have trouble beating Edward Martinez in a foot race. He won 10 Gold Glove awards, but now he’s mostly used as a designated hitter. The Mariners had a great season and everyone feels good right now. Leave while the afterglow is warm, say the critics, and make room on the roster for a young player who might be the Ken Griffey of tomorrow.

Admittedly the critics have a point, but I hope he stays anyway. The stats on paper tell only part of the story. And besides, didn’t everyone know all this about Griffey BEFORE the Mariners signed him a year ago? We didn’t sign him because we expected 30 home runs or acrobatic plays in the outfield. We wanted him because the team needed him and the fans wanted him. Here are five reasons why he should return for one final season.

1). Ken Griffey makes the Mariners a better team. The hugging and high fiving in the field and in the stands after the Ms won their final game last Sunday made you think they made the playoffs. Compare that to the bad feelings all around just one short year ago, when the team lost 101 games. By all accounts, Griffey has been an inspiring, unifying force in the clubhouse, a mentor to younger players, and a good friend to Ichiro. Morale means victories and Griffey is good for morale.

2). Griffey brings out fans. Dollar for dollar (his salary is a fraction of what it was in the 1990s) he probably delivers as much value as any veteran player on the roster. The Mariners became a good team in 2009. They might become a good one in 2010. Why miss the ride?

3). Right now Griffey, a first ballot shoo-in for the Hall of Fame, has 630 home runs. That puts him 20 from 650, a nice round number to retire on and one last goal to shoot for.

4). He is still having fun. For Griffey, baseball isn’t about money. It’s not about redeeming himself. He has nothing left to prove. He is playing for the sheer joy of the game itself. He is now as much a part of this town’s landscape as Ernie Banks was in Chicago or Cal Ripken in Baltimore.

5). That brings up a fifth reason for wanting Griffey back. It would give the fans in Seattle – and everywhere else – a chance to give a suitable sendoff to someone who’s done so much for the game. From avoiding the juice, to spending lots of time with Make-A-Wish children, to working himself back into shape after injuries gave him an excuse to check out, Griffey has become a great ambassador for the game itself. He likely wouldn’t want all the fanfare and pre-game ceremonies that were part of Ripken’s last season. But the gratitude expresses what people most love about the game.

If he decides to leave, I’ll certainly understand why and respect his decision. But I hope he gives it one more year. Just one.