The Premier League season is now well underway, and each side has played six matches, giving onlookers plenty of opportunity to assess relative strengths and weaknesses.
Some sides have enjoyed their start to the new campaign, while others have either underachieved or are already beginning to look like relegation fodder.
As such, here's a quick guide to the one standout problem which looks as though it could hamper each side during the course of the league season.
Negating these weaknesses—or failing to do so—could make all the difference between relative success and failure as the Premier League moves forward.
Let's take a look.
The Gunners have made an outstanding start to the season—save the opening-day loss to Aston Villa—which has seen them jump to the top of the Premier League table and take six points from six in the Champions League.
Additionally, Arsene Wenger's men are playing arguably their best football in the last four to five years. But how long can it last?
Arsenal have a very strong starting XI, maybe even 14-15 players, capable of matching pretty much anyone. Additionally, they're flush with attacking midfield talent and they have a crop of excellent youngsters lower down the chain. But they remain sparse in some areas.
If striker Olivier Giroud—who has been outstanding in 2013-14 thus far—gets a knock and has to sit out a few games, can anyone do his job to similar effect? Mathieu Flamini was only a free transfer, but Arsenal have no one else like him in that defensive midfield area and the Frenchman's impact since his return cannot be underestimated. Nor can that of Per Mertesacker, who has become the side's defensive leader.
As such, if Arsenal are to continue setting the pace this season, they may well need a little bit of luck where injuries are concerned. And that's something that cannot be guaranteed and hasn't happened too often in recent campaigns.
With their pacey front trio of Christian Benteke, Andreas Weimann and Gabriel Agbonlahor, Aston Villa boast one of the Premier League's most fluid forces where counterattacking is concerned. Just ask opening-day victims Arsenal, or even Manchester City—even if both Benteke and Agbonlahor were missing that day—about their threat.
However, the worry comes when the opposition sit men behind the ball and say to Villa, "Break us down." Without space to exploit and if Benteke isn't truly at the races, the Villains simply don't carry the same threat and struggle to take the game to opponents happy to sit back and play on the counter themselves.
Witness the match against Liverpool, who, having taken the lead at Villa Park, were content to keep Villa at arm's length, backing that their opponents lacked the craft to break them down. Or Alan Pardew's Newcastle, who escaped the Midlands with a 2-1 win and only conceded through a goalkeeping error.
Ashley Westwood is a talented deep-lying playmaker, while Fabian Delph, now fully fit, is an energetic presence alongside him. But alongside that duo and behind the front three remains a glaring hole which Paul Lambert needs to fill: someone who can control and dictate affairs in the opposing half and can unpick the lock of a crowded opposing defence.
Malky Mackay's Cardiff City have made a solid start to their Premier League debut, taking eight points from their opening six games. Compact, well-organised and sprinkled with added quality following a summer of big spending on key players like Steven Caulker and Gary Medel, the Bluebirds have been pretty much as expected, if not slightly better.
Nonetheless, there is still room for improvement within Mackay's favoured 4-1-4-1 formation, mostly in an attacking sense. Simply, Cardiff can be relied upon to be defensively pretty tight and to be a threat from set pieces, but they still need to find a consistent goalscorer.
It was something that they pretty much did without winning the Championship last season—Peter Whittingham and Aron Gunnarson led with eight each—but the Premier League is a step up, and a striker who can score 12 plus goals can be invaluable.
Andreas Cornelius, Peter Odemwingie and Frazier Campbell are the prime contenders for the main striker role, and Odewingie has form from his time with West Brom. Hopefully, he can be the man Cardiff need.
Much has been made of Chelsea's galaxy of attacking stars over the course of the summer, with Jose Mourinho's fridge stocked with the kind of offensive talent other managers not named Pep Guardiola, Carlo Ancelotti or Gerardo Martino can only dream of.
However, while the attacking midfield line is well-stocked and Mourinho still has a group of excellent defenders to work with, there is little balance elsewhere.
Up front, Romelu Lukaku, arguably the club's best striker, has been allowed to go on loan to Everton, Fernando Torres remains hit and miss and is now injured, Samuel Eto'o is far from the player of his Barcelona and Inter Milan pomp. Demba Ba, meanwhile, simply hasn't convinced.
In the holding midfield roles, other than the energetic Ramires, no one has laid claim.
Frank Lampard is a club legend, but the first half against Spurs proved that sitting in midfield is far from his best position, while Jon Obi Mikel isn't positionally aware enough to play as a part of a double pivot—indeed, it's a stark contrast to when he plays as a sole holder in a 4-3-3.
As such, Mourinho has to find the correct balance, in terms of personnel, all across the park.
Who plays wide, who plays up front, who is his No. 10, who are his holders. Additionally, the Portuguese needs to find the right tactical setup—be it 4-2-3-1, 4-3-3 or another—to bring the best out of his individuals and quite simply to answer the question: What is Chelsea's best team?
They've made a decent start, but there are unquestionably improvements to be made.
Already, Ian Holloway's Crystal Palace appear doomed.
It seems harsh to say given that the league season is only six matches in, but it appears that the Eagles are nothing more than a Blackpool light (Holloway's last crack at the top division), and they don't have Charlie Adam at the heart of their midfield.
Defensively, they give a lot away looking to play from the back. What they wouldn't give for a Kevin Phillips some 12-13 years younger up front, and the midfield just doesn't appear up for it.
Summer spending has seen the likes of Jimmy Kebe, Adlene Guedioura, Barry Bannan and Dwight Gayle come in as well as a raft of others, but are they of the required quality to keep them in the Premier League? Additionally, is Holloway tactically astute enough to keep them in the division, having only won promotion by the skin of their teeth?
Having lost five of their first six matches, the answer would appear to be no.
The 3-2 home victory against Newcastle perfectly encapsulated the problem Everton have as they transition away from the David Moyes era to that of new manager Roberto Martinez.
The first half saw the Toffees playing with the flair, style and panache that the Spaniard wants, and their creative efforts were rewarded with three unanswered goals.
However, in the second half, they appeared to be trapped between continuing with the Martinez way of working possession and attacking and the tried and tested way of their former manager when working with a lead: sitting back, keeping things tight then looking for opportunities as they present themselves.
Thus, caught between two stools, they conceded two goals as Newcastle attempted to mount a comeback. While Everton could have scored one or two themselves, they could easily have thrown away the three points they appeared to have guaranteed prior to half-time.
Certainly Martinez is doing things his way, and with the blue half of Merseyside still unbeaten in the league, he's doing them particularly well.
But there are still some old habits from the Moyes regime that he would do well to keep a hold of if he's to keep Everton punching above their weight.
Looking at Fulham's team on paper, it is packed full of mercurial talents in the shapes of Messrs: Dimitar Berbatov, Adel Taarabt and Bryan Ruiz. In that trio and the likes of Darren Bent, Damien Duff and John Arne Riise, Martin Jol has put together a team of artists, brimming with attacking intent.
However, alongside the artists, all great sides need their artisans: players who can put in the hard yards and do the graft and whose personalities shine to such an extent that those aforementioned artists realise the need to put in some of the hard yards themselves for the greater good.
Simply, the Cottagers don't have that.
Scott Parker and Steve Sidwell are competitors, but neither is a particularly vocal presence. Indeed, Fulham aren't a particularly outspoken team, and during the last eight months or so, Jol's side have become far too easy to play against.
As such, they've won just two of their last 14 Premier League matches and tension is starting to engulf Craven Cottage. They need to get back to basics and hard work or they could be surprise relegation fodder in a tight division.
Save the opening 45 minutes against Chelsea where Mourinho's Blues could have racked up five or six rather than just two, Hull City have made an impressive return to the Premier League.
And much of the credit for that has to go to Steve Bruce, who has really evolved as a manager during his 15 months on Humberside and is looking like the man who led Birmingham with such conviction a decade or so ago.
Having toyed with different formations during their promotion success last season, Bruce hasn't been found wanting in the top division,. His signings during the summer have largely impressed, particularly Tom Huddlestone, who is looking like a possible outside bet for a World Cup place.
However, what the Tigers desperately need is a goalscorer.
Danny Graham, for all his good work, just doesn't look like the answer, and Hull need someone who can partner the pacey Sone Aluko and who will convert the chances created by the likes of Robbie Brady.
Ten points from six matches is an outstanding return considering the two defeats came at Chelsea and Manchester City and that they've only scored six goals thus far. With a 15-goal centre-forward, a top-half finish may not be out of their grasp.
Sitting second in the table after six matches, Brendan Rodgers' Liverpool have made a tremendous start. Daniel Sturridge and Luis Suarez are a formidable strike partnership, the centre-half positions are filled with quality and they've looked good going between a back four and a three-man defensive line.
However, their start isn't without a worry, and that is their somewhat soft centre, particularly in midfield. And especially as matches enter the final third.
Whether by design or simply due to the amount of energy expended in the opening 60 minutes of matches, the Reds have been visibly dropping off the play later in matches.
It is during those moments that opposing sides are increasingly creating chances through midfield, bypassing Lucas and Steven Gerrard with a certain degree of ease. Witness Swansea's second goal in the 2-2 draw and Jonjo Shelvey's unchecked run or the goal Sunderland scored in their recent match: a shot from distance, under little pressure, resulting in a Emmanuele Giaccherini tap-in (albeit in the 52nd minute, but you get the point).
It is something which the Reds cannot continue to allow to go unchecked, as it will keep costing them points as the season progresses. How Rodgers rectifies it, whether through tactical or personnel changes, is the question.
Just what happens to Manchester City when they play away from the Etihad Stadium?
At home, Manuel Pellegrini's side are pretty much perfect, having taken nine points from nine available, scoring 10 goals and conceding just one in the process while destroying both Newcastle and Manchester United.
Yet on the road, they seemingly keep their hand hovering over the self-destruct button. And every so often, they slip.
The 0-0 at Stoke was respectable; the Britannia isn't the easiest place to go and City made a lot of changes that day. However to lose 3-2 at both Aston Villa and Cardiff after having led on both occasions—twice at Villa Park—is careless to the extreme.
Whether it's a mental, technical or tactical problem, it's something that City need to get a handle on.
Otherwise, it could not only cost them their title challenge in a league where the battle for the top four appears more open than ever, the points they throw away could cost them a place in next year's Champions League.
Moving on from Sir Alex Ferguson after over 26 years under his stewardship was never going to be easy. And it hasn't been.
And while the players remain the same as those who claimed the title last season with such relative ease, they aren't performing like them. A perfect encapsulation of what is wrong with the new incarnation of Manchester United was shown during their home loss to West Brom.
Having equalised through Wayne Rooney, under Ferguson, United would have immediately stepped on the offensive, pressing the opposition to give them the ball back at the soonest available opportunity. Having been hammered the previous week by rivals City, it was the least you expected: United to push on and look for the three points.
However, on this occasion United didn't apply any kind of exerted pressure and allowed Albion to play passes amongst themselves for a good 45-60 seconds and calm themselves down.
It was a small thing, but how often since the Premier League's inception have we seen United equalise and then take the game by the scruff of the neck, immediately getting on top of their opponents before getting a winner? Plenty.
This time, however, there was no intensity and United merely settled into a pattern of aimless meandering. Saido Berahino's goal condemned them to a much-deserved defeat. The midfield woes have been well-publicised, but it's the need to refocus that is a more pressing concern.
Away from the mounting pressure on Alan Pardew and Joe Kinnear's mysterious presence in the background, Newcastle are simply a side from that you don't know what you're going to get.
On paper they've some tremendous technical players—Yohan Cabaye, Hatem Ben Arfa, Davide Santon—and have the makings of a good side. But quite simply, you don't know whether they're going to turn up.
Man City on the opening day was a write-off. The following matches against West Ham and Fulham were hard fought and they claimed four points. Following the international break, they claimed a smart three points at Villa Park with a slick counterattacking display, but followed that up by throwing away two leads to lose 3-2 at home to Hull City.
Finally, they rounded off September with a game of two halves at Everton, being utterly lamentable, as they conceded three in the first half before showing spirit and determination to score twice in the second.
Quite simply, their inconsistency is painful.
Painful for their supporters and manager Pardew, who must pull his hair out those weeks his side simply don't turn up. He needs them to find consistency, as much for his job security as anything else.
Chris Hughton is a more than decent manager and he's done a good job since succeeding Paul Lambert at Carrow Road. But the thing working against him is that he's a reactive coach.
What I mean by that is, he sets up his team to be defensively solid and to stop the other team; he reacts to them rather than instigating proceedings. It's his go-to move; the only time it hasn't been is at Newcastle United, when he had a team head and shoulders better than any other in the Championship.
However, he does have a crop of talented attacking players at his disposable. Robert Snodgrass, Anthony Pilkington and Nathan Redmond are all wingers with contrasting skill sets, but all are capable. Leroy Fer is an outstanding central midfielder who wouldn't look out of place with Champions League regulars. Gary Hooper is a proven goalscorer.
The Canaries have claimed seven points from their opening six games, doing so while scoring just four goals. With a little more attacking thrust and impetus and greater aggression when in control games, they could perhaps think of finishing comfortably in the middle of the table.
Southampton under Mauricio Pochettino are presenting themselves well as one of the Premier League's more upwardly mobile clubs. And after spending big in the summer on key additions and having claimed 11 points from their opening six matches, such assertions certainly have their merits.
Moreover, with a crop of fine young players who are only going to improve and a brilliantly organised defensive game that has seen them concede just two league goals so far, they certainly seem set to go places.
However, what the Saints do need is a greater cutting edge in the attacking third—they've only scored five goals themselves—and they need to find a way to fit talisman Rickie Lambert and record signing Pablo Osvaldo up front together playing as a partnership rather than individuals.
If they can't get the pair working as a cohesive unit, then the hard choice will come down to Pochettino to select one and make them the spearhead of his side. With Messrs. Adam Lallana, Jay Rodriguez Gaston and Ramirez vying for places also, they have some good forward players, but they need to start firing.
Mark Hughes has continued with the Tony Pulis way of keeping Stoke City ultracompetitive, albeit with a sprinkling of more aesthetically pleasing football. However, the signs are that the Potters are set to struggle with the same old problem: scoring goals.
Last season saw them the Premier League's lowest scorers besides bottom-of-the-table QPR, with the Staffordshire club netting on only 34 occasions. And they've continued in a similar manner this campaign, with only four goals scored in their opening six matches.
Hughes has adjusted the Potters midfield and their style in a bid to enhance their creativity this season. Steven N'Zonzi has more attacking license, Stephen Ireland could prove an astute pick up when fully fit and Marko Arnautovic has the unpredictable talent that can unlock even the stingiest of defences.
But up front, at the point of their 4-5-1 formation, Hughes is still stuck choosing between Peter Crouch (seven goals in his last 38 league matches) or Kenwyne Jones (three goals in his last 31). As the 1-0 loss at home to Norwich showed, scoring goals is still a problem for the Potters.
The Paolo Di Canio reign is at a premature end, but in his rear-view mirror, he has left a Sunderland side looking painfully devoid of confidence, and that has taken just one point from their opening six matches. In short, he's left a mess.
The concession of 14 goals hints at a weak defensive structure. Only four goals have been scored at the other end, and the vast overhaul of the playing staff undertaken over the summer has, from the outside looking in, only made things worse.
Chief goalscorer Steven Fletcher continues to struggle with injuries, Jozy Altidore is yet to break his duck and Stephane Sessegnon, their main creative spark, was sold by Di Canio.
Additionally, is there a Premier League side with weaker starting full-backs? After all, the Mackems have been playing midfielders in Jack Colback and Craig Gardner in those positions lately.
All in, it's one hell of a job for the new manager, whoever he will be. He'll have to do quite the job if he's to lead the Wearsiders to safety.
Forget the balance sheets, the television deals and the need to be where the money is: Football remains about glory. Swansea City proved as much last season with their Capital One Cup success.
And that in itself poses a new question to the Welsh club this season: Is safety merely enough?
Having tasted what it's like to win something, is it enough for the Swans to just spend their immediate future looking to safely maintain themselves away from the Premier League danger zone? Surely not.
And credit to manager Michael Laudrup, who has so far juggled his squad between league and European ventures—we'll discount the League Cup debacle at Birmingham—allowing his players a shot at a competition which they can make a serious splash in this year. They aren't going to win the Premier League, nor are they contenders for European football because of it, so why shouldn't they prioritise Europe?
As such, Laudrup needs to find the right balance between enabling his players to compete in Europe this term while keeping themselves out of danger back home. Rotation and keeping players fresh will be vitally important—Alan Pardew's Newcastle showed how difficult it could be last year. Hopefully, Laudrup can have more success, and we should applaud his willingness to challenge European football's secondary competition.
After all, football remains about glory.
Tottenham Hotspu, under Andre Villas-Boas have made a very bright start to 2013-14, and 13 points from six matches is a good return for a new-look squad.
Defensively, they've been outstanding, conceding just twice. At the other end, they've only netted six goals and new striker Roberto Soldado has yet to score from open play.
Certainly the 28-year-old Spaniard is Villas-Boas' preferred No. 9 in his 4-2-3-1 formation, and the hope is that when Christian Eriksen and Erik Lamela have settled down, chances will flow more easily for the former Valencia man.
However, his two penalty winners aside, Soldado hasn't really done much at the beginning of his Spurs career. When he isn't scoring, he does have the tendency to go missing, and that's something that can't have gone unnoticed during his early days in the Premier League.
If Spurs are to make a run at the top spots this season, then they'll need Soldado firing on a regular basis. The sooner they can get him scoring, the better.
To expect similar this season would be foolish; a good season for the Throstles would be another of relegation avoidance and mid-table security.
Over the summer, they've lost a lot of goals with Romelu Lukaku and Peter Odemwingie's departures, while first-choice 'keeper Ben Foster picked up an injury. Prior to their last two matches—the victories over Sunderland and Manchester United respectively—going back to November 28, they had taken only 25 points from a possible 87—relegation form.
They have a new crop of attacking players, encompassing the likes of Nicolas Anelka, Stephane Sessegnon, Morgan Amalfitano, Scott Sinclair, Victor Anichebe and youngster Saido Berahino. While the recent victories have been good, can they do it consistently?
As such, expectations need to be tempered. It's a season where Albion fans may be wanting a repeat of the last campaign, but they may have to settle for another season of consolidation.
Sam Allardyce's West Ham made a strong return to the Premier League last season. While his detractors will always claim him a long-ball merchant, he's a far better manager than he's often given credit for.
Under Allardyce, the Hammers are strong through the centre, well-organised and tough to beat. Certainly they don't mind taking the direct route when Andy Carroll's there. But they also like to play their football: Mark Noble, Razvan Rat, Ravel Morrison, Joe Cole and Matt Jarvis are not bruisers happy just to play for aerial duel after aerial duel.
In the last 15 months or so, Allardyce has put together a decent Premier League side capable of scoring in a variety of ways. However, key to each of those ways is Carroll, who became their record signing this past summer. With him out injured this season, the Hammers have looked somewhat toothless up front.
Modibo Maiga simply isn't good enough; Carlton Cole hasn't been re-signed and wouldn't be the answer if he were; the experienced Mladen Petric remains a sharp finisher, but has seen better days.
As such, the Hammers are struggling to take their chances, while the impact of Kevin Nolan decreases in his absence. The East Enders need to keep as close to mid-table as possible in the England striker's absence before looking to rise when he returns.