Activision Blizzard has quietly shuffled its senior management team, divided itself into four decks and deleted 15 workers.

The outfit has apparently restructured without telling investors or the public. In fact the whole thing only came to light when internal memos were found by The Times Newspaper.

Activision Blizzard has split itself into four, with one focused on the military video game Call of Duty, another handling other company-owned titles such as Guitar Hero and the Tony Hawk skateboarding games, and a third handling licensed properties. Blizzard Entertainment, maker of the successful online game World of Warcraft remains independent unit.

Mike Griffith, who was a big cheese in Activision's non-Blizzard business gets the title of vice chairman. He will advise Chief Executive Bobby Kotick. Thomas Tippl, formerly chief financial officer and chief corporate officer, has been named to the new position of chief operating officer. He is now the only executive reporting directly to Kotick and oversees Blizzard President Mike Morhaime. He also gets to be the head of Activision publishing, something he has been temping in.

Activision Blizzard has done jolly well lately with its blockbuster success of November's Call of Duty: Modern Warfare 2, which has generated more than $1 billion in sales. Apparently sales of its music franchise Guitar Hero have plummeted faster than a team of free falling elephants without a parachute.

It is the first time that there has been a restructuring since Activision merged with Vivendi Games in 2008 to create Activision Blizzard.