The issue is Matt Ward is clearly not a bad writer from GW management perspective, as he has been let loose on a large amount of the new codex books in 40k. So GW clearly don't care what he is putting is terrible, as long as it sells.
I used to enjoy the fluff in the older army books. Some of the ones I have from the 90s [4th ed undead book comes to mind] have some really good fluff in. The more recent books, especially in the last year or two, are a steaming pile of..... well you get the idea.
On the plus side, a lot of the 5th ed books he has written are quite well done from a rules perspective. Not all, but most of the Matt Ward books do have a number of competative builds, where the older 4th edition books sometimes really struggle to make a competative build against 5th edition books.