Mariano Rivera #42 of the New York Yankees pitches against the Baltimore Orioles during a game on April 30, 2012 at Yankee Stadium. - 

Before Mariano Rivera, relief pitchers were seen as erratic starters past their prime. Rivera couldn’t be a starter, he only had one pitch, but that pitch was a killer fastball that cut at the last moment. And he rarely choked under pressure. By the late 1990s, every general manager wanted his own Mariano Rivera.

“This was your relief ace to nail down a game and if you didn’t have this guy, you couldn’t hold leads," says Brien Jackson, who writes for the blog, It’s About The Money.

Many relief pitchers who came after Rivera were overpaid -- and that created a market bubble. So a crafty general manager like Billy Beane of the Oakland A’s would let a decent closer save a bunch of easy games, "and then he’d flip them to other teams for assets that he thought were more valuable,” explains Jackson.

Around 2005 -- the bubble burst.

“Teams have finally started to realize that closers are actually made, not born, and you can find dominant relievers from the scrap heap," says Matt Meyers is an editor for ESPN.com.

Mid-level closers may not get the huge contracts anymore, but they’ve earned more respect since Rivera took the mound.