t's funny how the first half of a season can set the impression of an entire campaign in stone... and it's even funnier how false those impressions often turn out to be.
Take 2010-11. Chelsea seemed nailed-on certainties for a second successive title; Blackpool, meanwhile, appeared destined not just for survival but also for a spot in mid-table. Two years earlier, it looked like Luis Felipe Scolari had adapted effortlessly to English football. In 1995-96, it appeared as if Kevin Keegan would end Newcastle United's long wait for a title. And, three years before that, it seemed Manchester United's would stretch to 27 years.
Ultimately, though, none of those early-season 'truths' transpired and the 2011-12 Premier League campaign may well have its own versions.
After all, in the first few months it didn't just look like Manchester City would win a first title in 44 years but that they would romp to it with a record point tally. Spurs, meanwhile, seemed well capable of challenging at the top, let alone qualifying for the Champions League. And, at the other end of the table, a woeful Wigan seemed doomed. Evidently, much has changed. Changed a lot.
The following table shows just how much, as well as illustrating how dangerous it is to make any definitive judgments on the first half of the season. It is ranked on the order of improvement/decline from a team's first 19 games to their subsequent 13/14 (Aston Villa and Bolton have a fixture still to play):
While some of these just put numbers on what we know - Everton and Sunderland have dramatically improved; Wolves have imploded - the scale and identity of others are hugely surprising.
Spurs, for example, haven't just gone off form - they've almost collapsed, earning a full point per game less. As it stands, that is one of the worst drop-offs in league history. Liverpool, meanwhile, aren't far behind.
Remarkably, it's Fulham who are the most upwardly mobile - and most underappreciated - risers. Equally, Norwich and Swansea have so far avoided Blackpool's problem and are actually picking up steam as the season wears on.
Elsewhere, despite the supposed extremes of their season, Arsenal's form has actually remained quite constant. It seems that the depth of their dips - a succession of bad Premier League defeats followed by elimination in all cup competitions - falsely coloured their overall consistency.
Finally, before the 4-0 victory over West Brom, Manchester City had endured a drop-off almost as bad as Newcastle's in 1995-96 (-0.63). But that very result - and the alteration in stats and mood it brought - does raise other issues. Because these trends have potentially huge consequences for the tail-end of the season.
Given the basic importance of psychological momentum at this point, there seem to be a few probabilities that can be derived from the averages. In the Champions League chase, form and belief are clearly with Newcastle while, at the bottom, the fact that all four teams have actually improved raises the prospect of every broadcaster's fantasy: a final-day four-way battle for survival complete with images of grown men crying.
But, as City illustrated against West Brom, the big question is about understanding how these changes came about and what can be done to change them back. With some teams, it seems to be a simple case of requiring time to develop sufficient understanding and integration. At Fulham, notably, Martin Jol has gradually got his array of talented attackers to play much more fluently and regularly, easing the pressure on their defence.
Likewise, Roberto Martinez revealed at this exact point last year - when Wigan were about to enjoy a similar surge - that the inevitable sales the club endure every summer mean players in an altered squad have to relearn the necessary approach for their intricate passing style. "We had a difficult start and delayed the process," he said. "It's a real shame that we haven't got another 30 games to go because I think we would see the real measure of this squad."
By contrast, more one-dimensional teams seem to just go stale - particularly when they pick up key injuries. Stand up Aston Villa and, to a lesser extent, Liverpool.
You couldn't accuse this Manchester City of being one-dimensional but there does seem to have been an issue with going stale. Earlier in the season, as a restructured forward line spearheaded by Sergio Aguero and guided by David Silva took teams by surprise, they also took them by siege. Once the second round of fixtures came around, though, many sides had taken a look at City and changed up accordingly. Roberto Mancini didn't. And, as a result, his attackers were going down the same avenues but not finding the same exits.
Indeed, like many clubs, he could have learned from Newcastle. Up until January, Alan Pardew's side seemed overly dependent on Demba Ba. But, just as the season entered its second half, the manager admirably changed shape. Ba was moved out to the left, Hatem Ben Arfa found his groove on the right and January's most expensive player, Papiss Cisse, became the new focal point of an unorthodox 4-3-3. So, just when opposition sides might have sorted out a plan for Newcastle, Pardew - and specifically Cisse and Ben Arfa - sidestepped them.
Another impressive aspect of Newcastle's surge, though, has been Pardew's personnel management. His squad have a much greater spread of players with 10-25 appearances than a number of the top clubs - including City and Spurs.
As such, they've so far remained fresh enough to successfully implement Pardew's gameplans. Likewise, it's no coincidence that the three longest-serving managers in the Premier League - Sir Alex Ferguson, Arsene Wenger and David Moyes - have all facilitated teams that are either improving or just consistent. Ferguson, after all, is the master at rotation, built up from years of finetuning. Moyes does have a perennial issue with slow starts but his Everton side are always ferociously fit going into the final stretch.
Which brings us to Spurs. Naturally, a decline that extreme has more than one major cause. Indeed, it's a culmination of all the above.
For one, Harry Redknapp has ludicrously overplayed his first XI as he sought to wring the most out of a front line that was then, admittedly, exceptional. Spurs have seven players with 29 appearances or more - the most among the top teams.
So, not only is their intensity inevitably lessened but Redknapp clearly doesn't trust any alterations. The majority of his changes have either been cosmetic or self-defeating, like the recent shuffling of Luka Modric and Gareth Bale.
On top of all that, there has been the confusion surrounding Redknapp's court case and his next job. Suddenly, that looks slightly less certain - but that's only in-keeping with many early-season 'truths'. The key, now, is whether they can force more changes in the finish.