Let us talk about Reverse Engineering.
It is a concept that takes an existing Thing, and tears it a part to figure out how it works.
In the crooked path of tangent dead ends, LOST as a "Thing" needs to be de-constructed in order to find any salvageable, redeeming cohesion to the Ending.
To preface the following, I have no doubt that TPTB had any clear road map to the Ending. All the creators had was the final image, of a plan leaving the island. How the show found its way to that point was a twisting path of "character development," strange events and odd back stories. Some may imagine that all the character filler was compressed so tightly that the end created a seam of coal. Or in the bedrock of the story lines, there may be a glint of some untapped jewel; a theory that not only unifies all of the LOST world views, but turns the Ending upside down from the stand point of a secondary character.
As previously posted, in order to get a full picture of the debris field of the 815ers story lines, one has to examine the wreckage from a different perspective.
When a writer sets down to create his master works, he knows the basic elements of a story: a beginning, a middle and an end. Character, action and resolution. How those pieces are interwoven are the key to the reader's understanding and appreciation of the whole work.
Now, some writers know of the general plot line before writing their story. Some may pencil an outline of characters, actions, events, issues to be resolved. Some writers may just start with a title and forge forward with their chapters, with the twists coming from their creative minds free style. "Making it up as it goes" has some advantages and some disadvantages. It allows one's mind to roam free to make connections not already penciled into a steady outline. It does allow one's free form approach to veer off course. The danger is losing track of the pieces that comprise a satisfying resolution.
But for many mystery writers, the key to their stories ending properly is that they write the ending first. There is a common sense notion to knowing how something will end before you begin the journey. And that approach is what I used to try to find greater meaning to the End of LOST, by reverse engineering the finale. To answer the question posed: who was the wizard behind the curtain?