Arsenal and Chelsea had pretty well-defined patterns of spending - the Gunners spent little and often, primarily on the best young talent, while the Blues splashed out on Europe's big hitters, often for record fees - but all that's changed this summer.
Arsene Wenger has shifted his transfer focus away from teenage talent and towards established internationals, while Roberto Di Matteo has re-calibrated Chelsea's focus, choosing to hone in on the game's best young players.
£25m for the 20-year-old Oscar and £32m for the 21-year-old Eden Hazard are unprecedented purchases under the Roman Abramovich regime - only the £19m spent on a 19-year-old John Obi Mikel comes close.
Instead, Chelsea preferred to bring in the likes of Ashley Cole, Andriy Shevchenko, Didier Drogba, Claude Makelele, and Fernando Torres - all 25 years old and over, and all for substantial fees.
But, beginning with Romelu Lukaku's arrival in 2011, and continued with the £8m purchase of 19-year-old goalkeeper Thibaut Courtois and 19-year-old midfielder Oriol Romeu, Chelsea notably and deliberately switched focus in the transfer market.
Part of this can be attributed to the failed Andre Villas-Boas revolution. Charged with overhauling the Chelsea squad, AVB's downfall in March last year briefly halted the youthful revival at Stamford Bridge before it had really begun.
Under AVB another £7m was spent on Kevin de Bruyne and £6.6m on the 17-year-old Brazil starlet Lucas Piazon.
But while Roberto Di Matteo's initial reflex was back towards the old guard, he now seems to have taken up the mantle carried forward by his former-boss.
But crucially for Di Matteo, he earned the respect of the club's dressing room generals - the likes of Frank Lampard, John Terry and Didier Drogba - through his Champions League management, before gradually ushering in the changes.
AVB's mistake was introducing those radical changes - however needed - before establishing his authority within the squad. Now there's a real sense of a changing of the guard at Stamford Bridge. Next year, the squad will be young, vibrant, and for the first time since Jose Mourinho's Damien Duff and Arjen Robben 4-3-3 formation, exciting to watch.
Across London, Arsene Wenger has moved in the opposite direction. The shift began this time last year when a panicked Wenger - having lost Cesc Fabregas and Samir Nasri - turned to Per Mertesacker, Mikel Arteta, Andre Santos and Yossi Benayoun.
That trend has continued this year, with £10m apiece spent on Lukas Podolski and Olivier Giroud, and a slightly higher amount - reported to be £12m, rising to £17m - on Spain star Santi Cazorla.
All three are established internationals, all at least 25 years old, and all will immediately challenge for a first-team place. In the past, Wenger may have signed one or two older players, Tomas Rosicky or Andriy Arshavin for example, but by and large, the emphasis remained on attracting the continent's best young talent.
Players like Theo Walcott and Alex Oxlade-Chamberlain were brought in as the focal point of a transfer window - but fans had to be patient to watch them graduate to the first-team. The fact that when they did it often wasn't long before they left for Manchester City or Barcelona didn't help endear Gunners fans to Wenger's philosophy. So the last three transfer windows - including this summer - feels like a real sea change at the Emirates Stadium.
Of course, it wouldn't be summer without one Arsenal star threatening to leave, but whispers now suggest Robin van Persie could stick around after all. Fed up of watching others leave and lift trophies, perhaps Wenger's signings have provoked a rethink by the Dutchman.
In Manchester, it's all quiet - and unnervingly so. City have all the cash, and everybody nows that - getting value in the market is difficult enough, but it's almost impossible for Roberto Mancini.
After the excesses of recent seasons, City are yet to make any moves this year. But, unlike Chelsea and Arsenal, don't expect any shift in the City transfer policy. Rather, their inaction is less through design, and more due to market pressures.
Each year, one or two transfers seem to hold up everybody else. This year, that transfer seems to be Luka Modric, as once Spurs get the money from Madrid, they can sign Adebayor, which will then help free up City.
Their city rivals in Stretford, long since moved on from Modric, concluded shrewd deals early on in the window, but have been chasing the big names since to no avail. Shinji Kagawa for £17m was an excellent bit of business, and Kagawa, along with Nick Powell, fits neatly within Sir Alex Ferguson's transfer criteria - value for money, at a young age and with huge potential.
Ferguson has been vocal in his pursuit of both Lucas Moura and Robin van Persie, but both deals look further away now than they have done for several weeks. And £30m-plus for Lucas Moura would have been a surprisingly high figure for United - but not unprecedented - Wayne Rooney signed as an 18-year-old for around £25m.
Worryingly for United, Ferguson's inability to clinch the big deals is becoming something of a trend. Luka Modric, Eden Hazard and Samir Nasri have all slipped through the net in the past 12 months, while Lucas and RVP don't look likely anymore.
While United have been concerned with arrivals, on Merseyside all the talk has surrounded departures. Liverpool's targets haven't been quite as pricey as United's and Chelsea, but, like Spurs, the appointment of a new manager has galvanised the club's transfer policy, as the new boss looks to clear-out and bring in his own players.
Under Kenny Dalglish the emphasis was primarily on British talent, Stewart Downing, Andy Carroll and Jordan Henderson were brought in for a combined £65m.
New Liverpool boss Brendan Rodgers has signed Italy striker Fabio Borini, but is looking to raid his previous club for Ashley Williams and Joe Allen.
Tottenham's new manager Andre Villas-Boas has wasted no time bringing in Jan Vertonghen and Gylfi Sigurdsson.
And AVB will be hopeful that, with or without Modric, Spurs will be able to capitalise on last season's fourth place finish and improve further.
For Arsenal, despite the good work in the transfer market, a question mark still hangs over the future of Robin van Persie. Their season, and a potential title challenge, rests with van Persie.
Without him, Arsenal will struggle to challenge the top two but likely be good enough to hold on to a top four place. But with him, and Cazorla, Podolski and Giroud in the squad, the Gunners could be set for a first title challenge in recent years.
But they'll have to watch out for Chelsea. For the Blues a top four place is a must, and if Hazard and Oscar settle quickly, and Fernando Torres rediscovers his form - all big ifs - Chelsea will be a title contender next season.
There's plenty of time yet, but Manchester City and Manchester United have stood still relative to the transfer activity of Arsenal and Chelsea. Whether the London club's moves pay off next season, only time will tell.
But, by changing tack, and changing philosophy, they've given themselves every chance.
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