The decision to move Triple H to SmackDown was actually made back around the time the deal with MyNetworkTV was reached. The network knew from the start that they would be marketing the show around The Undertaker and Triple H as the two biggest stars.
Right after WWE’s European tour after WrestleMania, The Undertaker, Edge, Vickie Guerrero and Triple H were brought in to the studio to tape promos for MyNetworkTV. Triple H’s promo had him spitting water into the camera saying, “You’re watching Friday Night SmackDown right here on MyNetwork TV.” The fact that Batista wasn’t there for the promos shows that the decision was made that far back.
Those promos will begin airing this fall. Only a few people knew of the promos and had to sign a non-disclosure agreement which expired on 6/24, because the info was released on 6/23. The actual filming was finished in April and the ads were completed in late May.