This season's Champions League semifinals don't feature the four most outstanding goalkeepers, defenders, wingers or strikers in the world, but it's difficult to argue with the selection of deep-lying midfielders.
In Sergio Busquets, Andrea Pirlo, Xabi Alonso and Toni Kroos, we're being treated to an exhibition of probably the world's four most revered footballers in that role. Between them, the quartet have won the last three World Cups and seven of the last 12 Champions League titles. More crucially, in different ways, they've helped redefine the nature of their position.
Stylistically, 21st-century football can be neatly summarised simply by charting the progress of various players in that primary midfield role. There's a notional Claude Makelele-Andrea Pirlo axis that every deep-lying midfielder can be placed upon, according to whether they're a pure defensive midfielder like the former, or essentially a bonus playmaker in the mould of the latter.
For so long, Pirlo was the "exception" in modern football, to use Pep Guardiola's words, the only true regista when everyone else was concentrating on destroyers. Even then, he was always fielded alongside Gennaro Gattuso for both club and country, an acknowledgement that defensive duties and work rate were still desired in that role.
Pirlo has received the most acclaim during his Juventus days, particularly at Euro 2012, when he was absolutely outstanding for Italy. There's a good argument that players in his role peak around the age of 30 because it's a position that depends upon intelligence -- which improves with experience -- rather than explosive movement -- which declines with age.
But Pirlo had also been outstanding during his 20s, slightly overlooked in a superb AC Milan side that featured other superstars like Kaka, Rui Costa and Clarence Seedorf, and dominated European football during the middle of the last decade. Milan won two Champions League titles, and should have won a third -- but for a shocking collapse in the final against Liverpool in 2005.
That was the first time Pirlo encountered Alonso, and this was a particularly notable match because it demonstrated what the deep-lying playmaker couldn't do. Liverpool were ripped apart in that first half because Alonso was fielded as Liverpool's deepest midfielder, Rafael Benitez surprisingly deciding to omit Didi Hamann from the centre of the pitch. During his period at Liverpool, Alonso generally excelled when alongside a positionally disciplined defensive midfielder, like Hamann and later Javier Mascherano. When asked to protect the defence on his own, Alonso struggled.
That came as no surprise and Hamman's half-time introduction for Steve Finnan rescued the game. But, jump forward a decade, and now both Pirlo and Alonso are being fielded directly in front of the defence without the support of a player in the Gattuso or Mascherano mould. What, during that time, has changed?
There are probably two main factors. First, the game has become more technical and less physical generally, allowing these gifted, wily footballers to operate in front of the back four without being overpowered consistently by opponents. In another sense the game has become faster, which means both Pirlo and Alonso can be vulnerable because they lack the mobility of others. Still, through good positioning without the ball, and authority and a neat first touch with it, this isn't a consistent problem.
Second, teams have become more organised as a whole. Some sides, particularly Diego Simeone's Atletico Madrid over the past couple of years, have taken this to an entirely new level -- the midfield is as organised as defences were a decade ago, the forwards participate more without possession than with it. Therefore, the role of the defensive midfielder doesn't have to be about darting across the pitch making crunching tackles, it's enough to remain in the right zone, track opponents when needed and make the odd well-timed interception.
Pirlo and Alonso are different players, however, to Sergio Busquets and Toni Kroos. These two are more defensively talented, even if both are still highly impressive with possession.
Kroos is a brilliant gifted all-round midfielder, who has played expertly as a No. 10, a box-to-box midfielder and now a deep-lying playmaker, at an amazingly early stage of his career. Kroos is similar to Pirlo in the sense that he initially made his name at the top of the midfield trio -- but just as Carlo Ancelotti oversaw Pirlo's positional transformation at AC Milan, he's done the same with Kroos at Real Madrid.
Kroos boasts greater physical qualities than Pirlo or Alonso -- for all his technical attributes, he's also 6 feet tall and extremely powerful. This means Real have often got away with using him, and two of Luka Modric, Isco or James Rodriguez in a midfield trio. That said, Kroos has barely been rotated this season, is coming off the back of a demanding World Cup, and looks absolutely exhausted. In recent weeks, defender Sergio Ramos has been fielded alongside him, perhaps playing the role of Gattuso to Kroos' Pirlo.
Then there's Busquets, the only one of this quartet never to have moved sides and therefore absolutely perfect for Barcelona's style of play. The fact that he replaced Yaya Toure during Guardiola's reign was significant, considering his predecessor -- then in his guise as a pure defensive midfielder -- was a more traditional player to have in that position. Guardiola saw something of himself in Busquets, and realised he needed someone who could position himself better and move the ball more quickly.
Busquets' personal development over the past five years has been fascinating. At the end of his final season with Barcelona he won the World Cup as Spain's primary midfielder, when he could count upon Alonso alongside him, a peak Xavi Hernandez ahead and Andres Iniesta drifting inside from the left. Busquets concentrated on defensive duties, and therefore earned a reputation as an underrated player -- which wasn't untrue.
But gradually, Busquets has become even better. And whereas the other three are creative players brought back into a more withdrawn position, the Barcelona man is a defensive-minded player who has been encouraged to be more creative.
In this respect, Busquets is the exception among this quartet: a proper defensive midfielder. That, in itself, is fascinating, considering that Guardiola once described Pirlo as "the exception" because he was the only top-level deep playmaker. In the 2006 Champions League semifinals, for example, Pirlo was present for Milan, but Barcelona used Mark van Bommel, Arsenal had Gilberto Silva and Villarreal relied on Marcos Senna. Even these good footballing sides used destroyers.
Now, we expect top-level sides to boast pure playmakers deep in midfield, a huge transformation in a relatively short period of time. Busquets, Pirlo, Alonso and Kroos are all different types of midfielders, but collectively summarise the modern game perfectly.