A beats B, B beats C and, well, C could end up walloping A. That's why a Manchester City side that looked humdrum against Cardiff, Hull and Stoke - four points in three games from sides likely to be in or near the drop zone this season - and humbled 3-2 by Aston Villa yesterday can go out and hammer Manchester United, as they did last week.
But performances do tell us something. In City's case, it's no coincidence that they struggled against four (relative) Premier League minnows who employed the usual English small-club mantra: effort, commitment, congested areas of the pitch and set-pieces. There's a learning curve for managers as well, and Manuel Pellegrini simply doesn't have much experience of sides like that.
United, on the other hand, are a Champions League team, of the kind he has crossed swords with plenty times. It's not necessarily that they were that much more expansive (they weren't) it's more a question of approach, mentality and familiarity. Wednesday's visitors, Bayern Munich, are obviously in the same category. And their visit doesn't come at a bad time. The afterglow of the derby win is still there for City and there is still a sense that the European champions have yet to be tested this year. The closest they've had to a genuine test was last weekend away to Schalke, and even that was only on paper. Schalke may be a big-name Champions League side, but they've also had a string of injuries, a horrid start and, as of Friday night, were just three points above the drop zone.
City will be different and fraught with peril, especially as Bayern are so much of a work in progress that you almost expect Bastian Schweinsteiger and Phillipp Lahm to show up wearing hard hats and workboots.
Pep Guardiola was hailed as a revolutionary and he has delivered his own revolution. The biggest switch is from 4-2-3-1 to 4-1-4-1 and the transition to a lone holding midfielder has occasionally left his back four exposed. What's more, he has - a number of times - played Lahm in that defensive midfield role, with Rafinha slotting in at right-back. Lahm is obviously a versatile player, but there have already been (and will likely continue to be) knock-on effects.
While the Bayern skipper learns a new position, the new Bayern right-back is inferior in terms of quality. Down the road, you will have issues of personnel too. If Lahm is in there, there will be just two central midfield spots left for Toni Kroos, Schweinsteiger, Javi Martinez, Thomas Muller and Thiago Alcantara to fight over. And that will test Guardiola's man-management skills even further.
Up front, there have been fewer changes. Arjen Robben and Franck Ribery are still allowed to play with the directness they showed last season. It's probably a wise move from Guardiola at this stage, if only because it's already far too much more about the manager than the players, according to some.
"Every day it's Pep here, Pep there, Pep up, Pep down," said Mathis Sammer, the club's director of football. "The players are hiding, everything is about the manager."
Until now Bayern have won through sheer talent, simply because they are better than everyone they've faced. But if Pellegrini can ride the Manchester post-derby confidence and enthusiasm, he can get a win that would likely send City on their way to where they've never been: through to the knockout stage of the Champions League.
So Paolo Di Canio has gone and, as we wait for his replacement to be named (the smart money seems to be on Gus Poyet), Sunderland face a home match against Liverpool with Kevin Ball at the helm. It's tougher next week with Manchester United in town.
Much has been made about Di Canio's turbulent reign, from the highs of the derby win over Newcastle and avoiding relegation to acrimonious relations with several of the squad. Who? Well, everyone, according to the media; those who were left out, overweight or unprofessional, according to the former manager's camp.
But that's the past, and in the present there's a team with one point from five games and a doom-and-gloom atmosphere hanging over it. What's interesting is that Di Canio also bore the brunt of the criticism for the club's summer signings. It's a textbook case of the media at best simplifying matters, at worst ignoring the facts. First and foremost, Di Canio didn't run the transfer campaign, Sunderland's director of football Roberto De Fanti did. Secondly, we're simply in no position yet to judge whether the newcomers are any good.
What we do know is Sunderland cut nearly 30% off their wage bill and ended the summer with a net spend of zero: not too bad in the current climate. Fourteen players came in, yes, and 10 went out, with two more on their way. More importantly, four of the newcomers are 20 or younger and another four were loan deals. The only significant money, £8million and £6m respectively, was spent on Emanuele Giaccherini and Jozy Altidore.
The former has been an ever-present in the Italy squad for two years. The latter won't be mistaken for Edinson Cavani any time soon, but still scored 28 goals last year in Holland and is starting centre-forward for the United States, 13th in the Fifa world rankings. You can judge Di Canio's performance thus far, but to write off the summer signings after five games is silly. If they get this appointment right, there is no reason why Sunderland can't stay up.
Chelsea and Tottenham sharing the spoils yesterday at White Hart Lane is, make no mistake, a point won for Jose Mourinho's crew. The game plan, all along, was to replicate what we saw at Old Trafford, a safety-first approach evidenced by the inclusion of Ramires among the three behind the centre-forward.
Mourinho necessarily changed at half-time, being a goal down, and Juan Mata conjured up the set-piece that John Terry nodded home. Beyond that, Chelsea didn't offer much but, at this stage, it's not really about that. After two poor performances against Fulham and Basel and an away trip to Bucharest coming up, the key was to avoid defeat and Chelsea did that.
As for Spurs, they missed the chance to go two-nil up just before half-time and paid a price for it. The trick now for Andre Villas-Boas is to build on what we saw in the first half.