Although they finished fifth and fourth in La Liga, both were out of sorts when they met Porto. Sevilla had failed to win any of its previous five games, and even then lost only on away goals; while Villarreal looked exhausted and had begun a slump from which it is yet to recover. That's not Villas-Boas' fault, but it is a gap in his credentials.
That doubt has since become a real concern. Away against Manchester United, Chelsea had the better of the game, created more chances than United (22 to 14), and yet was beaten 3-1. It was perhaps a little unlucky, but its openness had allowed United a route into the game. It was a similar sort of misfortune that led Sir Alex Ferguson to modify his approach -- at least in continental competition -- after the defeats to Monaco, Borussia Dortmund and Real Madrid that eliminated United from the Champions League in 1997, 1998 and 2000: better, he came to think, to have, say, six chances to nil than twelve to three.
It was a similar story on Saturday: Chelsea had 14 chances to Arsenal's 13, but lost 5-3. The former Liverpool defender Alan Hansen described Villas-Boas as "naive" after the game at Old Trafford, which drew an angry response. On Saturday, Villas-Boas again insisted he would stick to his "principles." This isn't as simple as playing football that is "too attacking" or "too defensive;" Villas-Boas' whole style of play is predicated on hard-pressing and winning the ball back high up the pitch; which is something it's almost impossible to do in a defensive manner, even if the risks taken while in possession can be varied. The question then is whether the openness Chelsea has shown this season is systemic, or down to poor application of the system.
Jose Mourinho, to whom Villas-Boas seems doomed always to be compared, liked to defend deep, which was part of his strategy of conservation of energy. Essentially that has been the Chelsea way ever since; even if new managers wanted to adjust things, they found a coterie of Mourinho loyalists reluctant to change and, as they got older and slower, unable to do so. This season, though, Villas-Boas has enforced the change.
Pressing isn't an easy thing to assess statistically, but the difference in approach can be seen in the fact that Chelsea has caught the opposition offside 4.4 times per game this season, as opposed to 1.7 last season. It is also committing around 40 percent more fouls per game -- another sign of a team seeking aggressively to regain possession -- but what is perhaps surprising, as Michael Cox points out, is that shots conceded per game is down by 21 per cent. On the face of it, that suggests Chelsea is defensively more sound this season than last.
Shots conceded, though, is a slippery stat. At least part of the reason that United has conceded so many shots this season is that there is a belief, derived from his record in Spain last season and his performance in the Community Shield, that David De Gea is susceptible to long-range drives. That encourages teams to take potshots from range, which may actually lead to good attacking situations being wasted. When pressing goes awry, it tends to yield one-on-ones -- as with Arsenal's first, second, fourth and fifth goals -- which, obviously, lead to goals more often than, say, contested headers from 10 yards or speculative drives from 20.
The question then is why Chelsea's line looked so shaky against Arsenal (and it should be noted that against lesser sides, teams without the same composure in possession or precision in the final pass and the finish, it hasn't been an issue). Part of the problem is Petr Cech. He seemed to be back to something approaching his best last season, but he was beaten on his near side by Andre Santos for the second, Theo Walcott for the third and Van Persie for the fifth. Occasionally a shot of unexpected venom will catch a keeper on that side; but three in the same half begins to look a worrying trend.
Then there is John Terry. Whether the ongoing investigation into an alleged racist comment is affecting his mental state or not, the fact is that he is a defender who likes the ball in front of him. What he's good at is big, bold challenges such as the one that led to his goal, Chelsea's second. Really, though, he needs an intelligent center back alongside him; the absence of Ricardo Carvalho is sorely felt. Play the ball in behind him, and with his lack of pace, Terry is never going to be able to recover; if he is to play in a side that presses high, he needs a rapid defender alongside him to bail him out, ideally one with the tactical brain to prevent him being exposed. This season, though, he hasn't even had a settled partner, never mine one who could guide him, as Alex, David Luiz and Branislav Ivanovic have operated as the second center back.
But then there is a general sloppiness: the chance Van Persie volleyed over after 12 minutes, for instance, came about because Mikel John Obi was drawn out of position as a result of Daniel Sturridge and Jose Bosingwa failing to close down Andre Santos. That in turn led to Ashley Cole being exposed against Theo Walcott. Similarly, the first Arsenal goal came about because Frank Lampard, distracted by making a point to the referee, left a gap for Aaron Ramsey to exploit, and then neither Terry nor Ivanovic followed Gervinho's run.
Bosingwa was hideously out of position for the Arsenal second; Mikel, Cole, Ivanovic and Terry were all caught napping by Walcott for the third, and the fourth stemmed from an awful Florent Malouda backpass even before Terry's slip. And that perhaps is the biggest issue for Villas-Boas: this is not one element of his defensive structure failing to function; it's repeated individual errors leading to an overall malfunction.
With a deep defense, players can occasionally switch off, and rely on those at the back to bail them out. With a high line, though, the whole team has to function as a unit; the slightest flaw will be magnified. Villas-Boas was able to achieve that at Porto last season, but the question now is twofold: can he get his side to function against the highest class of opposition, and will he be given the time and the budget to equip a squad more in tune with his philosophy? Roman Abramovich supposedly became frustrated with the functionalism of Mourinho's sides, but presumably what he wanted instead was not the sort of ragged carnival of Saturday.
Jonathan Wilson is the author of Inverting the Pyramid; Behind the Curtain; Sunderland: A Club Transformed; and The Anatomy of England. Editor of The Blizzard.