The messages the Mariners sent with Friday’s trade of their four-year opening-day shortstop Yuniesky Betancourt are as clear as mid-July in Seattle.

There is a right way to play the game. And a wrong way. There is a Mariners way. And there is every other way.

Watching Betancourt when he came to Seattle late in the 2005 season, you felt as if you were seeing the future.

He was a shortstop with some pop. A kid with a golden arm, range and a bazooka of a right arm.

He turned tough into easy in a way that Seattle hadn’t seen since Omar Vizquel. We hoped for ground balls into the hole, just to see what Yuni might do with them.

Sure, he could be a little casual with some of his throws. And sure, Betancourt was as anxious as a sprinter when he stood in the batter’s box. He lunged at pitches even Vladimir Guerrero wouldn’t chase. He cut percentage points off his batting average because he took cuts he shouldn’t take.

The old Mariners figured maturity would clean up Betancourt’s inconsistencies. He just needed a little more time to learn how to become a pro.

But Betancourt never grew up. He was the same here-today-gone-tomorrow player at 27 that he was at 23.

He was hitting .250 this season, more than 30 points below his career average. He was swinging at the same bad pitches and making the same sloppy plays in the field.

It seemed he would pay attention to manager Don Wakamatsu for two or three days, then slip back into his old habits.

Clearly, this new administration believed Betancourt’s time had expired in Seattle. Wakamatsu often talks about building “a belief system.”

Wak, his staff and the front office are looking for players who buy into that system, who believe in the Mariners’ way, who think the game as well as play the game.

They are looking for players who are resilient, not stubborn.

It is doubtful that third baseman Chris Woodward and shortstop Ronny Cedeno will be the everyday left side of the Mariners’ infield for long, but they do all of the little things correctly.

In many ways, their approaches to the game make them perfect role models for the dozens of young players in the Mariners’ system.

Betancourt was the anti-M. He didn’t buy into the system, and now he’s gone.

General manager Jack Zduriencik pulled off another gem, sending the cynical Betancourt off to Kansas City for 22-year-old pitcher Danny Cortes, who, if all scouting reports are correct, could be in the Seattle rotation by 2011 or 2012. Cortes was the Royals’ 2008 minor-league pitcher of the year.

This is exactly the kind of trade a team in transition needs to make. But just as important, it’s the kind of trade that lets every player in the organization know that the kind of sloth and stubbornness and lack of attention to detail often demonstrated by Betancourt won’t be tolerated.

This was a trade that had to be made, and the fact Zduriencik got value in return is something to celebrate.

Sure it’s a gamble, but the Mariners did the right thing, finding a new home for Betancourt and a new pitcher for their future.