Maul fanboys.
There's only so many excuses one can make for a character's incompetence.
It's much like any moderate interpretation of - batten up the hatches - the Quran, that comes full with justifications for it's central theme. When I started reading the Quran, my first thought is "this is a rant". After several pages in, I realize that's not what it is. It is a chant. A highly repetitive sentiment that could be summed up with - God is Great, the Disbelievers will be Punished - That is the central and primary theme of the entire book. Just as monotheist sympathizers recant the true message of the Quran, insisting it's a practice of non-violence, Maul fans are guilty of delusions of grander for their horned champion. Unaccepting of that he is, at the very core of his character, a failure as a Sith assassin.