I feel like VVD has exceptional football intelligence (in addition to having perfect physical and technical qualities for a CB), but he's literally the opposite of a player like John Terry in terms of intensity, which happens when someone is so naturally talented. He will actively switch off during games.
Lovren to me seems like he wants to give off the same air of superiority that he's similarly talented, but he's clearly not. I feel like he's very mentally fragile, don't get me wrong, he has good attributes and can look good when his confidence is up, but it's very easily knocked. If VVD makes a mistake for example, I don't see it affecting his performance at all, you can tell his confidence is real. To me the perfect CB next to VVD is someone who maybe not as talented, but has that dog in him. A Jamie Carragher type if you will, someone else with a real alpha mentality. I actually think having that style of player next to VVD would even help him a bit with some of the mental lapses. Any true top class CB would do me though.
No matter what you think of Lovren as a footballer, it's important to know that this actually couldn't be possible.
You look at the year he had outside of football and a mentally fragile person simply wouldn't be able to function with that going on. That just isn't up for debate. You can talk perhaps about concentration, decision making, that he tries so hard to make up for a mistake that it creates a vicious circle perhaps. But he isn't mentally weak.
Another good example of this is given in the Melissa Reddy piece on Klopp this week. It mentions how at half time in the away leg at Man City, Klopp walked into the locker room to find Lovren tearing strips off the team. Klopp, realising that Lovren had done his team talk for him, agreed with Lovren - then criticised the him and VVD also for being too deep - then pointed out what they should be doing second half to avoid more of the same.
You can see how highly respected Lovren is in the squad. You also know that he is seen as a leader by the players. Anybody who was mentally weak wouldn't be able to command that respect or position of leadership in a group of competitive men. It just wouldn't work as a dynamic.
This isn't to say Lovren isn't without fault - just that the leaps people make to explain the cause behind those faults are usually way off the mark.