Malingas problem as a test bowler was he was class at unsettling batsmen but didn't get the wickets. against england in 2007 they hated playing him.
his bounce can be lethal, I remember that cricinfo column written by chopra described him as one of the scariest fast bowlers around because his bouncer was very difficult to spot coming, but bouncers aren't the best balls to take wickets with.
he needed to find another way of getting wickets or sri lanka needed a partner for him.