Personally, I think it's great if Lovren gets a couple of games under his belt. Matip and Van Dijk have obviously done a good job together, but if Matip were to get injured (not going to speculate on the other one getting injured) we'd need Lovren to be ready to play. Sure, all that time in training will help him, but genuine match play will do even more.
Even if there's no further injuries at cb this season, there may be games where we want to do a bit of rotation as we go deep into two competitions.