At the time of writing, 52 percent of Chelsea supporters we polled on Branislav Ivanovic's best position felt that he is a centre back. As we heard on Saturday, Jose Mourinho disagrees, seeing him and Cesar Azpilicueta as the right backs in the Blues defensive unit. The manager elaborated a little on the official site:
Branislav Ivanovic I think more of using as a right-back. I see Ivanovic and Cesar Azpilicueta as our two right-backs, but also Ivanovic is very comfortable playing central defender. I asked him about that and he said it doesn't matter where he plays.
He is very comfortable on the ball but because he has physical adaptations to both positions it is easier for him to play right-back and now and again play central defender than the opposite.
When he is playing central defender and sometimes he goes to right-back, from the physical point of view it is a completely different dynamic in terms of the needs of the position. It is more difficult for a central defender to play right-back than for a right-back to play central defender, but from a technical point of view and the pleasure to be on the pitch for him it is exactly the same.
I can't really speak to the difficulties of switching from centre back to full back and vice versa, at least at the professional level, so I'll just have to take Mourinho's word that it's easier to go from wide to the middle than the other way around. It does sound like he's willing to use Ivanovic in the centre as circumstances dictate, but at the same time he's almost certinly not going to be our primary option there.
That said, Mourinho hasn't actually touched on where he thinks Ivanovic is at his best. Let's give that a go here.
For most of his Chelsea career, Ivanovic has played at right back. That's more to do with necessity than design, as the injury (and subsequent incompetence) sustained by Jose Bosingwa in 2009 has meant that we were fairly light at that position until the signing of Cesar Azpilicueta. Last season, however, Ivanovic spent much of his time in the centre, ultimately forming a rather good partnership with David Luiz.
There's no doubt that he can play both positions perfectly well, but at the same time he has obvious flaws wherever he's playing.
At right back, his relative lack of pace and technical ability (although the last one has always seemed to me to be a lack of focus rather than a dearth of talent) sees him either unable to effectively support the attack or caught out of position too often. At centre back, meanwhile, he has trouble reading the ball, often getting sucked underneath long diagonals, and as @chelseayouth pointed out yesterday, he often ends up marking his charges so closely that he can't adjust when they make runs.
It's striking that Ivanovic's issues at right back are stylistic rather than true flaws. Not all right backs are meant to attack, and their role going forwards depends on the system a team's playing. Consider, for example, Martin O'Neill's Aston Villa. That was a team that relied on wingers for width, which meant that the could use Carlos Cuellar, ostensibly a centre back, at right back to shore up the defence.
Chelsea's free-flowing attacking midfielders don't really jive with that sort of full back, however. Even if we have an Eden Hazard or a Juan Mata starting wide right, they'll rarely stay on the wing throughout the game, which means that the right back has to provide width. Ivanovic can do that, of course, but he can't do it nearly as well as Azpilicueta.
This suggests a more situational use for the Serbian than he (or we) might want. If using him as a right back solidifies the defence at the cost of the attack, than he should naturally be played in games where Mourinho's choosing to play cautiously rather than go all-out -- and I'd have to imagine that with the quality this squad possesses such games will be few and far between. That said, I've neglected an important piece of Ivanovic's play, which is his threat from set pieces. Ivanovic's ability to score from corners and free kicks negates a lot of his attacking flaws.
So, what's Ivanovic's best position? For me, it'd probably be as the right-most man in a back three, but as far as the back four goes, he's probably best served as a defensively inclined right back. That said, he's a good enough player to fit in at centre back or in a more attacking role when asked, and I'd hope that Mourinho isn't too rigid in his deployment.