John Rogers Script?

Was John Rogers the original writer for the film? I am confused because the original leaked script that came out a year and some months ago or however long it was had his name on it. Now I know Orci and Kurtzman have been credited with it but who is the mind behind the original story? Of all of the clips and book, and comics I have seen and read, the original leaked script seems right in line with all of them and only some small details seemed to have changed. When Orci and Kurtzman announced the transformers that would star in the film they acted like they had chosen them but werent they already pretty much in the original leaked script by Rogers? Save for the names being different on a couple, did Orci and Kurtzman really come up with anything creatively? I hear them talk in interviews about creative choices they made but wasn't all of that stuff already in the Rogers script? If this is the case then why are these two guys being hailed with all of the credit for writing this movie when it was someone else altogether who got it all started. Seems like they just came in and tweaked it a little and thats given them multi-script deals on major upcoming movies. Can anyone clear this up for me because I could be all wrong about this.