Haig was actually ore careful with the lives of his soldiers than some people think, field marshal French was replaced with hair, French was a bitter man who gained pleasure from belittling one of his better subordinates dorien-smyth.
He ruined his subordinates reputation and his own through blaming others for his mistakes and not following orders as well as being uncooperative with his French allies.
Having one of his subordinates took over because French had already besmirched dorien smyth.
With the nature of the fighting on the western front, how could haig of done differently?
The French replaced there generals constantly, but every time it all ended up the same, hundreds of thousands dead and injured for a few miles of land.
The truth is that Britain didn't have anyone who could replace him and do any better, the end results would of been the same. However the backs against the wall message and steadfastness of haig certainly helped save the british army in 1918.