What a difference a summer makes. Last season, Everton were amongst the Premier League's most impressive entities, transforming their playing style from attritional to aesthetic overnight and majestically marching their way to fifth in the English table.

Resultantly, manager Roberto Martinez, the mastermind behind it all, was linked with some huge jobs, including Barcelona, Arsenal and Manchester United.

This year however, neither the Toffees nor their impressive boss are in particularly high demand. Following a 1-0 defeat to Manchester City at the weekend, the Goodison outfit are now in 12th place - seven positions worse than this time last season.

So where's it all gone from for the Merseysiders? Our FIVE reasons should shed some light on the issue.

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The Full-backs

Standing still can often leave you dangerously exposed in the Premier League, but Everton's philosophy and tactics haven't really developed from last season.

Last term, full-backs Leighton Baines and Seamus Coleman were the Toffees' most important players; the focal points of the starting Xi and amongst Everton's most influential going forward:

It's a similar case this year, as detailed below, and you can hardly blame Roberto Martinez - Baines and Coleman are well amongst Europe's attacking full-back elite, let alone the Premier League's.

Resultantly however, the pushed-up full-backs are becoming a rather dogmatic ploy for the Toffees. Centre-halves Slyvain Distin and Phil Jagielka are often left exposed on the counter-attack, whilst opposition are now setting up defensively with deliberate intention to limit Baines and Coleman's influence as much as possible.

There needs to be more variation to Everton's play and greater protection for the back four. They've become hugely dependent on Coleman and Baines over the last few months for goals, chances and fluidity to their play, and that's made the Merseysiders dangerously predictable.

Injuries to John Stones and Ross Barkley

They may be amongst the youngest in the Everton squad, but Roberto Martinez clearly had huge plans for John Stones and Ross Barkley this season. Unfortunately however, both have endured considerable spells on the sidelines.

Stones started virtually every Premier League fixture for the Toffees at the start of the season, with his regular involvement even believed to have caused somewhat of a rift between Martinez and centre-back veteran Sylvain Distin, but the England international was stretchered off the an ankle injury against Manchester United in October and isn't set to return until the New Year.

Not only is the 20 year-old a fantastic prospect but his style of play is vital to the Toffees. He compensates for Phil Jagielka's limited pace and also brings the ball out of defence with magestic ease. Here's a look at Stones' stats this year compared to Everton's other centre-back options.

Likewise, although Ross Barkley has recently returned from a two-month knee injury lay-off, he's still yet to rekindle the form that saw him bag six Premier League goals last year, which are all veiwable below:

//www.youtube.com/embed/43uGzW05qyo

Statistically, this is actually the midfielder's strongest season for the Merseysiders:

But experimentation with his position, as detailed below, has limited the 21 year-old's ability to affect matches - and particularly, the scoreline - in quite the same way:

EUROPA LEAGUE

Harry Redknapp described the Europa League as a 'killer' and a 'nightmare'during his final season at Tottenham Hotspur - indeed, Europe's second tier competition does have a way of chewing up and spitting out it's participants, often destroying their domestic form.

Take a look at this infographic for example, produced by Whoscored.com last week, showing the league positions of Europa-League-involved clubs across Europe's top five divisions:

Pretty grim reading unless you're a Napoli or Wolfsburg fan, and the Toffees have particularly struggled to prioritiese between continental and domestic success.

They're flying high in the tournament itself, currently undefeated in Group H despite facing some challenging opposition:

But Roberto Martinez isn't blessed with the biggest squad, resulting in the likes of Leighton Baines, Phil Jagielka, Romelu Lukaku, Gareth Barry and Tim Howard already making 18 appearances or more this season, which has undoubtedly contributed to the Toffees' continuous injury problems.

Likewise, neither Martinez nor Everton as a club are particularly experienced in European football, so it's no surprise they're struggling to cope with it's added demands this year.

Investment in Barry and Lukaku

Everton found themselves in a rather unique situation this summer, in that they invested £32million - equalling 84% of their entire summer transfer budget - on players already at Roberto Martinez' disposal last season.

Indeed, Gareth Barry and Romelu Lukaku both emerged as integral performers for the Toffees last season, the former excelling in his anchor-man-come-third-centre-back transitional role, and the latter finishing up as the club's top scorer in the Premier League with 15 goals - viewable below. Understandably, that convinced Roberto Martinez to purchase their services outright at considerable cost.

//www.youtube.com/embed/M5MmtvNaXjU

Statistically, both are yet to match the form of their loan spells - although that's largely expected, considering the Toffees have only bagged four wins this season.

But the real issue is once again a question of progression - whilst the rest of the Premier League spent the summer improving their sides, or at least attempting to, the Goodison outfit spent £38million but have been left with virtually the same squad and starting XI as last season.

Age taking its toll?

They say age is just a number, but you have to wonder whether Everton's squad age is linked to their league form this year. As shown below, the Toffees actually boast the third-highest average age in the Premier League:

That's hardly surprising, considering Sylvain Distin, Phil Jagielka, Tom Howard, Gareth Barry and Samuel Eto'o - all of whom have started regularly this season - are all 32 years of age or older. The Frenchman for example, is an incredible 37.

Perhaps a speculative point but nonetheless one to consider; are Everton's most dependable players, such as Barry and Jagielka, in addition to Steven Pienaar and Leon Osman, simply too far past their best?

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