It appears Di Matteo has just seen what could happen with Luiz playing in midfield.
So what's different about Roberto Di Matteo's Chelsea compared to Villas-Boas? It's not a trick question, but it does have a lot of answers. Let's take a look at a particularly prominent concern - his flexibility as a tactician.
Being tactically flexible is a good thing. The very best coaches all demonstrate an ability to identify what needs to be changed and how things can be changed. Mourinho was particularly good at this, having the ability to constantly be on the lookout for subtle changes to shape and system which need to be counteracted upon in order to maintain control. Of course, too much, and you cause imbalances and confusion, as did Ranieri, or too little, and you lose control of the match, as in Ancelotti.
Villas-Boas was reasonably flexible in his approach, having the nerve to change his team's shape as required, and infamously against Valencia, being able to drastically change his team's approach. This wasn't why he was sacked as Chelsea manager, obviously, but it's an interesting difference between his reign and the current manager, where Roberto Di Matteo has gone about things rather differently.
Where Villas-Boas was flexible in terms of the players as a collective, individually he was afraid of making changes to player positioning and selection. Very rarely did he gamble on say, playing Ramires out on the left, or Daniel Sturridge likewise. While he did, in the case of the latter, make the striker play in an unfamiliar wide position, this was merely the confirmation of a process iniaited by Ancelotti. In this sense, Di Matteo is different. His shown in only five games that he is happy for his players to play as needed, best elucidated by the positioning of David Luiz in a right back role two more times than he was ever under Villas-Boas.
While this is a good thing - player versatility is extremely useful in today's squad game - it can also be a bad thing. As talked about in the Spurs analysis, constantly shifting your players can cause you to lose sight of why they do so well in their preferred positions. It is important, however, to keep in mind that Di Matteo's flexbility has extended to exposing the enhanced abilities of Ramires, and as such has had a positive impact on the squad, despite the negative image portrayed above.
I must compound on this negative imagery, however, when turning the attention to Torres. It was a key talking point amongst commentators and fans alike that Di Matteo placed Fernando, a centre forward, on the right wing. This wasn't especially a terrible move - the Spaniard has shown flashes of being brillant in deeper, wider roles - but it did reveal the inflexibility of Di Matteo in terms of shape.
Because its also important to note that another constant across the first five games is Di Matteo's retaining of the 4-2-3-1 more or less 90% of the time - illustrating the Italian's fondness for the widely popular formation and his desire to maintain the shape across most games.
This was best demonstrated when he introduced Salomon Kalou late in the Spurs game, where the Ivorian replaced Torres right wing position, presumably for the striker to be placed higher and more centrally, only for Fernando to be shifted across to the left. It was unusual, and it was bordering on completely silly. It seemed Di Matteo wanted to retain his 4-2-3-1 shape, no matter what, and keep Mata behind the centre forward. It's strange, really. While the caretaker is keen to showcase his flexibility when it comes to his players individually, he seems rather against changing the formation and shape of his side. In that sense, he represents quite a big deviation from the previous regime, and something that can be taken in both positive and negative ways.