To a certain extent Haig does deserve to be called a butcher and a bungler as his conduct in WWI proved poor. He was the architect of many of the British failures of 1915-18. In 1915 he was responsible for the offensive at Loos which resulted of huge British losses for very little gain. In 1916 he commanded the battle of the Somme for which he earned the title of “the butcher of the Somme” due to the massively high rate of casualties (60,000) and death (20,000) with almost nothing to show for it.
However, despite the multitude of failures Haig committed in the three years of war, he led what became the best 100 days of military history as he led the successful Allied counter attack in Marne that finally broke the military stalemate on the Western Front leading to the surrender of the German Army in November 1918.
Whilst Haig was not originally considered a great General and rose to his position through his friendships with powerful people, he did learn from his mistakes. By the end of the war he had learnt the power of the combined forces of air, artillery, infantry and tank offensive in battle and used this successfully in the decisive battle at Amiens. The idea that British generals were blundering old fools came from the public opinion after the 2nd world war where many thought that British troops were lions led by donkeys, examples of this are the 1969 film Oh! What a Lovely War and was reinforced by the Eighties television series Blackadder which describe him as an inarticulate, upper-class, charmless Scot, who owed his position largely to toadying to the Royal family via his lady-in-waiting