Donald and co show Gayle too much respect

Why does Allan Donald and the rest of the Proteas bowling coaching staff look so petrified when Gayle is hitting the ball everywhere in the ground?Surely they know what Gayle is about in limited overs cricket,so why don't they infuse the do-or-die attitude in our bowlers to combat Gayle?Remember what Biff did in a T20 match in England in 2009 to sort Gayle out cheaply.