It's 4%, AKA the Go Fuck Yourself Post.

[geng]

The amount of failure going into this thread is astounding. You are all making the assumption that each member of the raid has an equal chance to be targeted. The Anub'arak pursue is a fixate, which is why he can "randomly" switch due to priest fades and whatnot falling off or being used. Healers have a higher chance to be targeted due to the threat based portion of this.
http://www.worldoflogs.com/reports/rt-o ... ell/67574/
http://www.worldoflogs.com/reports/rt-c ... ell/67574/
http://www.worldoflogs.com/reports/rt-6 ... ell/67574/

its probably completely random for the first target, if it kills the target itll go on threat.