The tactical keys to Chelsea's Premier League-winning campaign
In the age of tactical flexibility and squad rotation, Chelsea's title has been built on old-fashioned principles. Jose Mourinho has stuck to the same 4-2-3-1 framework throughout the campaign and has used the same players: three are ever-presents in the Premier League, 10 have started at least 26 games and an 11th, Diego Costa, would surely have done likewise but for injuries and suspension.
Chelsea's triumph has been based on key performers playing key roles and, tactically, six men have been particularly important.
Costa starts at speed
Mourinho's increasingly regular complaint last season was that he had no striker. He set about remedying that by signing Diego Costa and, while the Spain international has only struck twice since the middle of January as his appearances have become rarities due to injury and suspension, he set the tone for the campaign with a superb start. Costa scored seven goals in his first four games, including two in the 6-3 win at Everton and a hat-trick in a 4-2 defeat of Swansea.
His shot map from those four games shows that the former Atletico Madrid forward was the penalty-box poacher Chelsea had lacked. Six of those seven goals came from 13 yards out or less and his long-range strike was from only 15. Costa rarely shoots from outside the box, but began in deadly fashion inside it.
Despite the recent suggestions Chelsea are boring, it is worth remembering they were prolific when Costa was a regular. After 22 league games, they had scored 51 goals, with him responsible for 17. He has only appeared in five of the subsequent 13 games, in which Chelsea have scored just 18 times.
It is also significant that Mourinho values a good start more than virtually any other manager. His teams tend to be front-runners in title races and prefer to have an advantage from an early stage. After four games of 2014-15, Chelsea were already five points ahead of Manchester City, six clear of Arsenal and seven better off than Manchester United.
Fabregas adds invention
If Mourinho addressed one weakness in his side by recruiting Costa, he rectified another by bringing in Cesc Fabregas, his other biggest summer signing, as a supply line. The two have formed a productive partnership; no other player has set up six league goals for the same teammate this season while Fabregas has provided another four for Eden Hazard.
Indeed, when Costa stopped scoring, the playmaker recorded fewer assists, leading Mourinho to defend him because, he said, he was still providing the passes. While it is looking less likely Fabregas will beat his former Arsenal team-mate Thierry Henry's Premier League record of 20 assists in a season, his total of 17 remains remarkable.
A map of where he was when he supplied those assists is instructive: Chelsea lacked creativity in the centre of midfield last season and Fabregas has showed he can be incisive from deeper positions. Indeed, he provided one pass -- for Costa and against Arsenal -- from within his own half.
It is also notable that five of those assists have come from corners. Chelsea do not overlook the basics and excel at set-pieces. They have plenty of goalscoring defenders, but Fabregas is their supply line.
Hazard hits the heights
The PFA Player of the Year is the favourite to win the Football Writers' award as well and yet, if those amount to recognition of the entire season, the Belgian has peaked at vital periods. Whereas Costa and Fabregas started superbly, only two of Hazard's goals came before November. Overall, he has been more potent this season and totals of 14 goals and eight assists show he can both create and finish.
Hazard is also two players in one, as his touch map for the whole season shows. He can hug the left touchline, stretching the game, which is particularly useful because Chelsea have a left-back, in Cesar Azpilicueta, who offers less width than many of his counterparts around the league.
Where Hazard is at his most dangerous, however, is coming infield into the inside-left channel. It was from there, for instance, that Hazard burst into the box to score his winner against Manchester United last month. The 24-year-old shoots almost exclusively from within 30 yards, within the width of the penalty box and normally on the left half of the pitch.
His combination of close control, ability to beat a man and shoot on his preferred right foot makes him particularly deadly from that area and also poses opponents questions regarding which of four players -- right-back, right-sided centre-back, right winger or right-sided central midfielder -- picks him up. Too often they don't have an adequate answer.
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Matic the mobile destroyer
While Costa and Fabregas arrived last summer, arguably Mourinho's planning for this campaign began in earnest in January 2014 when he brought Nemanja Matic back to Stamford Bridge.
The Serb has gone on to establish himself as the foremost defensive midfielder in the Premier League, winning the most tackles in the division this season. What a diagram of those tackles shows is that he is a very mobile destroyer, capable of getting out to the flanks to win the ball back and, in the process, arguably doing some of Hazard's defensive duties, as well as acting as a shield for his central defenders.
Mourinho, whose team beat Manchester United when they had the ball for just 29 percent of the game, has been publicly sceptical about passing statistics and Matic illustrates why. He enables Chelsea to win the ball back or to play without it. His positional discipline is also apparent: while he may roam from touchline to touchline, he rarely enters the final third. In other words, he is always in a position to recover.
Terry has been terrific
When Mourinho returned to Stamford Bridge in 2013, John Terry had finished a season where, due to injuries, suspension and the selections of Roberto Di Matteo and, in particular, Rafa Benitez, he had only started 11 league games. It seemed the captain was in decline and being phased out.
Those notions look wildly wrong now. Terry is an ever present in the Premier League and, having been Chelsea's third-choice centre-back, is now widely described as the division's finest. Mourinho said the 34-year-old's performance in April's 0-0 draw at Arsenal as his best in either of his spells at the club.
A map of Terry's clearances at the Emirates Stadium illustrates how busy he was and also shows how Mourinho has made the most of his assets -- heading, almost flawless positional play and concentration -- without his greatest weakness, a lack of pace, being exposed.
Chelsea often defend deep, so there is little room behind Terry for a speedy striker to accelerate into. He actually patrols a comparatively small area, with a defensive-minded, right-footed left-back, Azpilicueta tucked in alongside him and the division's best defensive midfielder, Matic, directly in front of him as the left of the duo in a 4-2-3-1 formation.
But Terry, and the defence as a whole, are a major reason why Chelsea have held their nerve in the run-in and at a time when they have been less prolific in front of goal. Since the 5-3 defeat at Tottenham on New Year's Day, which looks a freak result, they have only conceded twice in a league game once -- a 3-2 win at Hull -- and have only conceded eight times in 15 games overall.
Ivanovic offers energy
Some Chelsea players can be described as two players in one -- Hazard is a winger and a goalscoring inside-forward while Fabregas is a deep-lying playmaker and a goal creator -- and Branislav Ivanovic is another. The Serb has spent some of the title run-in as a right-back who rarely crossed the halfway line, tucking in alongside centre-back Gary Cahill to deny Manchester United and Arsenal space as each was shut out.
On other occasions, he can be perhaps the most marauding, buccaneering right-back in the division. Ivanovic's total of four goals and four assists shows he possesses more attacking threat than many a midfielder; arguably, indeed, than Chelsea's right-sided midfielders. Andre Schurrle and Mohamed Salah have left, Juan Cuadrado rarely plays and Willian is much less creative than his left-sided counterpart, Hazard.
Then look at Ivanovic's pitch map from the 5-0 win at Swansea in January. He was on the ball four times in the Swans' 18-yard box and set up Schurrle's goal. Two years ago, Ivanovic was Chelsea's first-choice centre-back but now he can pose more of a threat than many a winger. It shows the range of his talents.
Richard Jolly covers the Premier League and Champions League for ESPN FC. Twitter: @RichJolly.