This Theory that Mazzarin=Alric is based on one little conversation between a Shade and Alric.
It talks of the Shrine of Nyx killing Sinis.
Now this event must have happened after the Trows imprisonment (The Shrine of Nyx was probably in the Trow capital and this area would not thave been reached until the defeat of the Trow.) but BEFORE the total destruction of their culture. In and around Myth III. But that means that it could not be the Light Mazzarin but the Dark since Maz is dead by Connachts age.
So Sinis was probably one of the Avatara of the Wolf age and was killed by one Moagim-Reborn's Shades ei Mazzarin. Alric would have witnessed it as Moagim Reborn. Since they were enemies back then, Sinis and Moagim R. they don't don't talk too kindly of each other still.
This means that the Shade on "the Watcher" Was actually Mazarrin, he was changed to a Shade and was NOT Alric.