Mentioned this in the post-game thread, but two big reasons why he is vital for us now, and has looked better this year (and even more so on the right side.) He had a torrid start here, so no reason to revise the past, but he is important now - simple as.
Him being moved to RCB was a huge component because unlike with Moreno, he has an outside defender who can protect him. Also was why he looked better with Gomez next to him early on. That allows him to do what he does best - win aerial battles. Sakho sprays and tackles and Lovren clears, with each doing a bit of the other's main strength occasionally too. Sakho is decent, if inconsistent, but Lovren is an animal in the air, and we are missing that pure dominance.
I think it is pretty telling that we have a pretty good defensive record with Sakho - Lovren. They complement each other big time.