Trite Sloganism. War is complex and it's not a matter of just following steps and getting a job done. WW1 generals faced problems no generals faced before or scince. It was a war fought in uniqgue circumstances. Sure there were blunders it happens in all wars. WW1 a variety of factors came togetehr to make consequences of mistakes bigger. WW1 Generals were not particularly incompetent. Gievenr latiely evenly matched forces, given the techonlogical constrinats of the time, a bloody war of attrition is predictable result.That is a common fallacy, often used when criticisms are correct. If the plumber has been fixing your toilet and it still leaks, he hasn't done his work properly. You don't need to point out an alternative.
Besides the main alternative to attacking in the mud in Flanders is fairly obvious, isn't it? Not attacking.