Other regiments were wiped out, it doesn't of course mean there was bad leadership it could be other factors but it probably played a part.If you look at the number of contact battles that your "four years of World War experience" OC actually fought, once you allow for modern medicine and the resulting increase in survival rates of wounded, did they do that much worse than would a modern, thirty-something, decade of time served, officers when faced with a peer enemy?
Taking infantry battalions as an example, the Royal Scots suffered an 11% casualty rate across the whole of WW1 (they started the war with 2,000 regulars and 5,000 reservists. Roughly 100,000 served in the Regiment during the war, 40,000 became casualties, 11,000 died).
If you look at the the Royal Scots during WW2, the 8th Bn spent 10 months fighting in North-West Europe (June 1944 to April 1945), and lost 237 dead and 1019 wounded. 7th/9th Bn fought from the Scheldt onwards (October 1944 to April 1945), and lost 60 dead / 260 wounded. The reformed 1st Bn fought at Arakan, Kohima, and through Mandalay (1943 to 1945) - 146 killed, 476 wounded. Remember that an infantry battalion was about 1,000 strong in those days.
I'm not sure how or whether that can be compared with battalions on HERRICK or TELIC.
Of course, we'd like to think that the current officer career structure results in a far greater proportion of more competent and professional OCs - but are we sure of it? I suspect that the answer is that these days, we see fewer, utter, choppers in a position where they can really f**k up and get people killed - or perhaps the wartime battalions made up for that by being more willing to sack people before they got to that stage. I genuinely don't know.
Of course there are still utter buffoons serving now, but what could make or break a battle might be experiance.