Logic of openers?

The Ms have used "openers," relief pitchers employed to pitch the first inning of a game, setting up the scheduled starting pitcher to make his entry in the second inning.  The results have been mixed for the Mariners.  They have tried this ploy seven times, including last night, with mixed success.  Four times the opener has put the Ms in a three or two run hole; three times they have blanked an opponent.

I know this gambit was introduced by Tampa Bay last year,  but I'm not sure why they did it or why it makes sense for Seattle.  The logic, as I understand it, is this.  As the game has evolved starters rarely throw much more than 110-110 pitches, on average around 15 pitches per inning.  A good pitcher will  usually get in seven innings, which figures out to three times through the line-up, before being replaced by a reliever (usually a set-up man who is then replaced  by a closer in the ninth).

More to the point, the best batters usually are at the top of the order.  Using a opener means opponents first three batters, at least, will face a top-notch one-inning reliever and might only get two chances against the starter.  Saving that starter from having to face batters from top of the line-up a third time is a big advantage as, so the logic goes, the more times a hitter sees a pitcher, the more likely he will figure them out.

There's also an argument to be made that avoiding any runs in the first inning, especially in a home game, is advantageous.  No team likes to start in a hole.  That is, however, precisely where this tactic  has failed the Ms.  Ineffective openings have put them behind right from the start.

I don’t understand why the M's are trying this experiment, particularly given the poor quality of the team's relievers.  And why does Servais fo it for some stsrters, like Milone last night, but not other pitchers?