I just finished John Keegan, The First World War. I gather that he was seeing the changes in consensus and didn't agree. He seemed to think of all the Western front as trench warfare much of a muchness, though he does mention changes in tactics without emphasis. He also gives short shrift to the Eastern front and to the attacks on the southern Ottoman Empire.
There seems to be a change on thought now, going by such articles here as
May I ask: what books cover military strategy and tactics of World War I, following current thought and without so much of a focus on the Western Front?
Also, are there any magisterial overall books along the lines of Battle Cry of Freedom, a single volume that covers not just the battles, but also the leadup, politics, finance, production, trade, et cetera?
If you're after a book that goes beyond the Western Front while still offering a variety of material, I must recommend Matthias Strohn's World War I Companion, a marvelous collection of essays put out by Osprey in 2013. They range far beyond the usual, covering everything from the war in the air to the French army's struggles with tactical tradition to the German occupation of the Ukraine. The authors are all excellent, and the essays it includes are all reflective of the most modern schools of thought. I hope that it will be of help to you.
My personal favourite book regarding British tactical doctrine and technological development is Battle Tactics of the Western Front: The British Army's Art of Attack 1916-1918 by Paddy Griffith. Unlike Keegan who you are now acquainted with, Griffith approaches the battles of 1916-1918 through the lens of someone seeking to explore how these battles were different from each other. His focus is on tactical doctrine and in incorporation of new technologies into the planning of these battles. I used this book extensively during my Honours thesis and can highly recommend it. For artillery developments in particular, Fire-power: British Army Weapons and Theories of War, 1904-1945 by Shelford Bidwell and Dominick Graham is also a fantastic read though half of the book focuses on the Second World War.
Keegan is a fine military historian. But be aware that he is at least one and possibly two generations removed from the current state of historiography. I wouldn't so much say that he disagrees with the current consensus as that he is a product of his time and his works reflect an earlier state of scholarship. Academic history is best thought of as an ongoing discussion between scholars, and by reading older works like Keegan you are essentially missing more recent developments in that discussion. That doesn't make them bad or useless, but it is rather like watching a movie halfway through and then trying to discuss the conclusion.