After completing a deal to sign Nicolás Otamendi in the summer, Man City’s second consecutive year of spending a huge sum on a centre-back, observers could be forgiven for believing that the club had finally found their ideal partner for Vincent Kompany at the heart of their defence. Eliaquim Mangala failed to live up to expectations in his first season, but unlike with the Frenchman there were few questions asked upon his arrival about the genuine quality of Otamendi; alongside the also superb Diego Godín and Gerard Piqué, he was quite possibly the best performing centre-back in La Liga in 2014/15.
Half-way through this season however and the issues with the position, presumably much to the discontent of Manuel Pellegrini, are for now still unsolved. Kompany missing a significant number of games and thus leading to an unsettled back four certainly hasn’t helped, just like it didn’t the previous year either, but aside from some sporadic bright performances (his last three or four have been consistently excellent too, saying that) Otamendi has too often looked a very different defender to the brilliant one he appeared to be at Valencia.
Drops in performances like that regularly happen to players in all sorts of positions after transfers, and realistically that’s something which can be expected to occur if footballers are moving between vastly different environments and tactical systems when they switch clubs. Take another former Valencia player who struggled after a move to the Premier League, Roberto Soldado, for instance. The Spaniard’s heavily penalty area-based game was something which a Spurs side in large transition with no clear transfer plan was rarely set up to fully utilise, and as a result his performances in England never got close to how impressively he played in La Liga.
Alternatively, following on with the theme of strikers, Christian Benteke at Liverpool is a more recent example of a failed transfer and bad player profiling by the purchasing club. His lack of movement, poor contribution in build-up play and the reliance he places on a team to provide consistent service for him from wide areas – i.e. crosses – meant he was always going to be a poor fit in the team which was being built in a very different style by Brendan Rodgers at the time (and the one which Jürgen Klopp is currently moulding right now).
Perhaps a little less so in the case of Soldado because of Spurs’ circumstances, but those two transfers of players into systems which evidently didn’t fit them, both with and without hindsight, were practically doomed to go badly from the start. Or at the very least, it’s easy to analyse after the event and come to a firm conclusion of why things didn’t go well (or aren't going well) for those attackers. When it comes to defenders though, and centre-backs in particular, as Man City can attest to, it’s not always so simple to work all these things out.
That difficulty quite possibly comes down to the difference between the nature of attacking and defensive play. To say that attacking is simply an individual-based phase of play would be to oversimplify it massively, as the failures of those two strikers as well as the complexity and depth of concepts like Juego de Posición (something touched on in this piece on Bayern Munich and Douglas Costa) demonstrate, though in comparison to defending there is undoubtedly a greater element of individualism about it. A poor attacking structure can still be carried by talented players, but a flawed defensive system can’t be fixed just by having a couple of good defenders. Find any team that performs well defensively and it’ll be thriving because it’s exactly that; a team.
Because of this extra team-based nature of defending, establishing, isolating and then working out the importance of all of the different factors that have been involved in that player’s own performance becomes very challenging. If a centre-back playing in a high line is constantly exposed by balls over the top due to their team not pressing properly, it’s unfair to criticise just that player for having a poor game. Likewise, if an excellent team unit is regularly keeping clean sheets, attributing lots of praise towards one specific player during that run is likely to be unjust or unfairly weighted.
A defender can live by the system they play in, but they can also die by it. And, reverting back to the Man City example, Otamendi has undoubtedly been a victim of this. One of the core reasons for his success at Valencia was his partnership with Shkodran Mustafi, a measured and composed covering centre-back who provided the perfect foil for the Argentine’s front-footed, aggressive position-based style. Now without a defender of that mould to regularly play alongside him (Martín Demichelis is perhaps an exception, but Kompany and Mangala are similarly very aggressive), it’s not a huge surprise that his performances haven’t always held the same level.
The other really significant factor to consider, without going into too much detail about the Man City and Otamendi thing, is the Yaya Touré problem. Although still blatantly brilliant on a technical level, his defensive discipline and positioning skills leave a hell of a lot to be desired: a big issue when he’s playing as part of the double-pivot just in front of the backline. To be a centre-back behind the masses of space that Touré allows to be exposed is something which Kompany’s performances last season have shown to be a thankless and incredibly challenging task, and Otamendi’s finding out such a thing this season too.
And yet, by the same logic, there’s an argument to be made that maybe it was Mustafi, the excellent holding midfielder Javi Fuego, and Valencia’s defensive structure as a whole that actually made Otamendi look better than he is in 2014/15. Or possibly his true level lies somewhere in between these two extremes. His consistently high level of performances at Valencia and Man City’s previous history with centre-backs does suggest that his period in Spain is a much fairer time to evaluate his talent on, but that’s the thing – when the tactical circumstances are so different and there are so many factors to consider, it’s tough to decisively judge.
The difficulty in assessing defensive talent is also perfectly represented by analytics in football and the inability to judge these players with defensive action-based stats. Where it’s quite widely accepted that more is generally better in the case of attacking metrics like shots, key passes and dribbles, the same doesn’t apply for the defensive side of the game. Making lots of tackles and interceptions doesn’t make a defender good. The same applies the other way, too. Instead, those stats really just show how busy a player was (or wasn’t) in a match, or at best can be used as part of a broader set of data to get inferences of how a specific team defends; something which links nicely back to the more individualistic nature of attacking in comparison to defending.
Just a quick look at the defensive stats (per 90 minutes) from this season of six of the world’s best centre-backs, all in different teams, shows the inconsistencies and lack of correlation with them. Atlético Madrid’s Diego Godín might make at least twice as many clearances, interceptions and tackles per 90 than Jérôme Boateng does for Bayern Munich, for example, but what does that mean about them individually? Almost nothing. Is it evidence that proves one is better than the other? Absolutely not.
Again, all it really suggests is that one team or player defends differently to the other. Even to prove that, though, you need to use much more specific data like where they’re making these contributions or the amount of passes that a whole team allows per defensive action it makes. Otherwise it might just mean that an individual has lots of opportunities to reclaim the ball because their own side can’t keep possession properly in the first place.
To judge a defender by these actions alone would also be to completely disregard the art of positioning and reading situations, as well. And without a way to properly quantify such a key part of that phase of the game at this moment (there’s nothing really available for that on a public level, at least), there’s very little that defensive metrics can do to help us work out the true qualities of a centre-back right now.
That’s of course not all to say that it’s impossible to decipher how good a defender is. Because after watching them a lot and carefully considering all of the influences that contribute to the level of their performances, it’s certainly doable. Toby Alderweireld has seamlessly fit in at the heart of Spurs’ defence this season, being one of the league’s best performers after joining in the summer following a strong 2014/15 at Southampton, for instance, while the Saints’ signing of Virgil Van Dijk instead of the Belgian has similarly proven to be an excellent piece of business.
Without recreating an environment where lots of the factors that helped a central defender to be successful in the past are present in the tactical system, however, bringing a new one into a different side, perhaps more so than any other position on the pitch, is always going to be a big risk.