Amen! People don't factor in that every inning your closer pitches is a stress inning. THere is no (or very little) coasting thru a line-up with the comfort of a big lead for a reliever. In a lot of ways, market forces decide the game. You wouldn't make such good pitchers relievers if the job was not critical. Similiar to the "Pithching is 75% (or 90% or whatever) part of the game arguement" - if that was true, Babe Ruth would have never been taken off the mound. How the game uses it's talent dictates the relative importance of positions.
Especially in the case of Ruth, as he was going to be a HOF pitcher and only played once every 3 days the first 4 or 5 years of his career.
Think if he had played every day? He would have 1,100 homers....
Top relievers are paid top dollar per inning. Multiply Rivera's salary by 3 to make his innings comparable to a starter and he makes $30 million a year.
Best money George has ever spent.
Relievers are almost always guys who can't start effectively. Think John Smoltz and Curt Schilling after their injuries, Dennis Eckersley because he was losing it, Eric Gagne because he sucked.