The addition of Michael Cole to the SmackDown! announce team is a result of Vince McMahon's current unhappiness with Todd Grisham.
According to a source, McMahon cut one of his "famous Vince promos on an announcer" backstage in front of a lot of people and put Cole on the debut episode of SmackDown! on Syfy saying it was an important show and he wasn't getting the job done. The impression many got was that halfway through the show McMahon became unhappy with Grisham's commentary and sent Cole out to join them.
Cole was again on commentary this week and it is expected to remain a three man team until further notice.
More as we get it.