Most of the genuine low shots came right during that last flurry. I don't think Weeks was anywhere near assertive enough, and even though it really did look like Kovalev had already mentally checked out (which maybe would warrant a stoppage), that wasn't a good look. Those shots that Ward landed before he rocked Kovalev with the right hand looked fine to me, but during the last flurry, at least two of the shots were low (beltline was clearly said by Weeks to be fine, but some of those were below the beltline). It's pretty clear to me that Kovalev was done one way or another, though. He was hurt to the body and to the head and completely exhausted. Ward was obviously quite a bit sharper this time out (I was surprised to see him land his right hand up top as much as he did, as he has never really had a particularly good right hand), but if you're a fighter on the level that Kovalev is at, you shouldn't be gassing that badly (body work was a big factor, but to have almost nothing left in the tank by rounds 7 and 8 is not what you expect from great fighters). It does make you wonder just what was happening in his camp.
It's a shame that this somewhat strange ending is going to overshadow what is a fairly remarkable achievement. Very few people would have believed that Ward could stop Kovalev.