This season's Premier League was supposed to be the most tactically diverse ever -- in the end, the campaign was based almost entirely around Chelsea's switching system, and everyone else looking to copy them.
Chelsea's 3-4-3 and how teams played against them completely dominate our tactical review of the 2017 Premier League campaign...
Tactical decision of the season
Antonio Conte's decision to switch from a 4-1-4-1 system to a 3-4-3 back in the fall is probably the most decisive tactical switch in the history of the Premier League, let alone the most important one of the season.
The extent to which it revitalized Chelsea's campaign was remarkable. After the 3-0 defeat to Arsenal, they sat in eighth position, having been completely outplayed by both Liverpool and Arsenal to that point. But Conte's experimentation towards the end of the contest at the Emirates proved absolutely crucial.
Chelsea immediately embarked upon a 13-match unbeaten run and not conceding a single goal in the first six. David Luiz was masterful as the spare man, Marcos Alonso was a natural wing-back, N'Golo Kante could play his proper energetic role rather than sitting deep, Pedro could make his trademark runs in behind and Eden Hazard was freed from defensive responsibilities. Cesar Azpilicueta and Victor Moses adjusted perfectly to new roles, and Chelsea briefly seemed unbeatable.
93 points is the second-most in the history of the Premier League -- only behind their own record of 95 points from 2004-05. Just as Jose Mourinho shocked the Premier League with his use of 4-3-3, Conte's success owes much to his shift to a 3-4-3.
Tactical game of the season
This was supposed to be the most fascinating Premier League campaign ever, at least in a tactical sense, with the most exciting managerial lineup ever seen in English football. The two new arrivals were Pep Guardiola and Antonio Conte, and their first clash, at the Etihad in early December, proved the most interesting game of the campaign.
With Chelsea now established in their 3-4-3 formation, Guardiola decided to name a remarkable 3-2-4-1 system in order to stop Chelsea. This meant Chelsea's three centre-backs only had one player to mark and that Jesus Navas and Leroy Sane pushed Marcos Alonso and Victor Moses back, giving City a numerical advantage in the centre of the pitch.
And while City would eventually lose 3-1, they were utterly dominant in the early stages. Kevin De Bruyne was the star, eternally drifting right and fizzing crosses into the box -- one eventually was deflected into his own net by Gary Cahill. But De Bruyne turned villain when he somehow missed an open goal at the start of the second half, and from there, Chelsea rallied.
City's problem was the fact they defended 3-on-3 at the back, and one mistake could cost them. Chelsea's three goals all involved bypassing midfield and getting the ball into the forwards -- first Cesc Fabregas lofted a pass to Diego Costa, who outmuscled Nicolas Otamendi and fired home. Next, Costa turned Otamendi again and played in substitute Willian to fire home, before Eden Hazard rounded off the win by beating Aleksandar Kolarov and finishing on the run. Many of the games between the big sides were disappointing this season, but this one was thrilling.
Tactical Goal of the Season
Chelsea's opener in the 3-1 victory over Arsenal in early February received plenty of coverage -- because it was a highly controversial goal. Marcos Alonso towered over his compatriot Hector Bellerin to nod home a rebound, and collided with Bellerin at such speed that the Arsenal right-back was forced to depart with a concussion.
Yes, it might well have been a foul. But look past that, and this was a perfect demonstration of how Chelsea's system, which essentially featured a front five when the wing-backs pushed forward, was outwitting opponents playing a back four.
Arsenal's defence was initially in an entirely good shape. But then left-back Nacho Monreal was drawn to right wing-back Victor Moses. Laurent Koscielny, in turn, followed the run of Pedro, and his centre-back partner Shkodran Mustafi tracked Eden Hazard. This left Bellerin isolated against Diego Costa at the far post, with the striker slamming his header against the crossbar. Bellerin actually did well to recover in time to challenge Alonso for the rebound, even if he was inevitably overpowered from his standing start.
But this was exactly why Chelsea proved so dangerous -- their front five always had a man spare at the far post against a back four. Some suggested that Theo Walcott should have tracked back further and beaten Alonso to the ball -- but Walcott was playing wide-right in a 4-3-3. Winning headers in his own six-yard box is hardly the domain of a player in that role, which underlines just how much Chelsea's 3-4-3 was dragging teams out of shape.
Individual Tactical Performance of the Season
Few teams managed to stop Chelsea, and even fewer managed to nullify Eden Hazard. But Jose Mourinho did both in Manchester United's 2-0 victory over the champions at Old Trafford in mid-April, largely thanks to a masterful display from Ander Herrera.
United had been thrashed 4-0 at Stamford Bridge early in the season, and for the FA Cup quarterfinal trip to London, Mourinho named, even by his standards, a highly reactive team. He decided the only way to cope with Chelsea's wide players drifting inside and their wing-backs bombing forward, was to man-mark the former and use disciplined wide midfielders tracking the latter. It looked like a back six for long periods, but the game plan fell apart when Ander Herrera was dismissed for bringing down Hazard.
Ironically, it wasn't even Herrera man-marking Hazard in that game -- it was Phil Jones. But for their next meeting, Mourinho decided to play Herrera up against Hazard, and the Spaniard completely dominated. Hazard showed surprisingly little intelligence in terms of varying his position to cause problems, and Herrera had Hazard in his back pocket throughout.
What was most impressive, however, was the fact that Herrera also contributed to both of United's goals -- first curling a wonderful pass in behind the opposition for Marcus Rashford to finish, then crashing home the second himself.
Team tactical performance of the season
Chelsea had won 13 consecutive games and were eyeing up the Premier League record as they travelled to White Hart Lane for the final time in early December. Tottenham, however, outplayed them and recorded a hugely impressive 2-0 victory.
Mauricio Pochettino's men had prepared for the game with a 4-1 victory over Watford in a 3-4-3 system, the first time they'd played that way in the Premier League. Sure enough, Pochettino matched Conte's 3-4-3, and Tottenham went head-to-head with Chelsea across the pitch.
The crucial factor in their eventual victory, however, was their intense pressing. Mousa Dembele and Victor Wanyama overawed N'Golo Kante and Nemanja Matic, while Danny Rose pushed back Victor Moses and Kyle Walker nullified Marcos Alonso. With Chelsea pressing less intensely, Spurs' centre-backs could move forward and dominate the ball, with Jan Vertonghen particularly impressive.
It was notable, too, that Spurs' goals were almost identical. For both the opener and the second, Christian Eriksen exploited the fact that Gary Cahill was reluctant to move out of the defensive line (having already been booked when Eriksen turned him), and Dele Alli made runs towards the opposite flank and towered over Cesar Azpilicueta. Two Eriksen crosses, two Alli goals, and a hugely impressive tactical display by Spurs.