To be successful in major league baseball consistency isn't a superstition it is a prerequisite. One speaks of pitchers needing to be consistent in the delivery, consistent in finding their release point and having consistency in their control. Practice they say makes perfect that is all about establishing consistency.
BTW You all make it sound that bringing in your best pitcher in the 7th inning is a brand new idea, It has all been done before. If any of you can recall Dick Radatz. He was doing that in the sixties. He would come in in the 7th, 8 th or 9 th. I even think he came in as early as the 6th inning on one occasion. I recall watching a game in the early sixties from the right field bleachers. You could hear the explosion of the ball hitting the catchers glove way up in the right field bleachers. (Of course there were fewer fans watching the games back then.)
Another reason why there is less reason to bring your "best reliever" in before the 9th is that there are more high quality relievers today and more who can throw 95 and above today. Just look at the Yankees bullpen for example.