Roberto Martinez undoubtedly had an excellent first season at Everton. The Toffees finished fifth in the Barclays Premier League and qualified for the Europa League. This season though, despite comfortably progressing into the Europa League knockout stages, Everton have struggled to replicate their fine league form from last term, and currently occupy 11th spot.

It seems to be a case of one step forward and two steps back for the Toffees. Everton have secured just one win in their last six games in all competitions. After an impressive 3-1 home victory over Queens Park Rangers a week ago, the Toffees travelled to St Mary's, to face a Southampton side, who were also struggling for consistency. The Saints ran out comfortable 3-0 winners, leaving Martinez bemoaning his defensive woes in his post-match interview.

Everton, who were tipped to ruffle the feathers of the top four this season, certainly have to pick up their form if they are to better their 5th place finish from last year. Too many of Martinez's senior players have let him down so far this term. We take a look at the FIVE players who have disappointed the most at Goodison Park.

Sylvain Distin

First and foremost, Sylvain Distin has been a great servant to Everton over the years. The defender has been at Goodison Park for over five years and has played over 160 league games for the Toffees.

Unfortunately for Distin, at the age of 37, his best days seem to be well and truly behind him. Anyone at his age would struggle to keep up with the pace of the modern game, especially the relentlessness and speed of the Premier League. Due to John Stones' injury, the 37-year-old is probably playing more games than he would have anticipated this season. Martinez has also utilised him in the Europa League and the Capital One Cup this term.

On Saturday, Distin struggled to keep up with the pacey Shane Long, and the Saints' striker is not the first, or the last, who will give the Frenchman a tough time this season.

Phil Jagielka

Staying with the current defensive problems, if Distin is going to come under scrutiny, then so should the Everton skipper too.

Phil Jagielka hasn't been anywhere near his best for the Toffees this season. The England international issued a public apology after the disastrous 3-0 defeat at St Mary's on Saturday. He and his defensive partner Distin had a difficult time against Southampton, and they were both caught out on a number of occasions.

Like Distin, Jagielka is another player who's been an excellent servant at Goodison Park. But the Toffees skipper needs to stand up and be counted, and prove why he's the captain of Everton and England's first-choice centre-back.

Steven Pienaar

The South African has struggled to make an impact at Goodison Park this season. The 32-year-old has only made eight Premier League appearances for Martinez's side so far.

With the emergence of Ross Barkley, and players such as Kevin Mirallas, Muhamed Besic, Gareth Barry, Aiden McGeady and James McCarthy - all packing the midfield, Pienaar, who's in his second spell at Goodison Park, could be on his way out of Everton sooner rather than later.

When he has had his chance to shine this term, he hasn't done enough to make a significant impression to stamp down a place in the Everton starting line-up. Pienaar can expect some appearances in Everton's cup exploits, but his Premier League chances are surely going to be very few and far between.

Tim Howard

Tim Howard is another senior player who has underperformed for Everton this season. The American stopper hasn't been as consistent as the Goodison Park faithful have become accustomed to.

Howard seems to be struggling with the defence in front of him and is majorly suffering as a consequence. The 35-year-old, who has been an ever-present for Everton thus far, has conceded 27 goals in 17 Premier League games - only Queens Park Rangers and Leicester City have let in more. That's a worrying stat for the Everton fans, and it just confirms Everton's current defensive frailties.

Howard has now failed to keep a clean sheet in his last seven Premier League outings, and it's certainly an area that Martinez's side have to improve on drastically - if they are to hunt down a European spot.

Gareth Barry

Despite being one of Everton's better performers in the 3-0 defeat at Southampton, Gareth Barry hasn't been as effective for the Toffees this season as he was last.

Barry was suspended for the match against Queens Park Rangers last week - but Everton barely missed him - and won the game comfortably. But Martinez shuffled his team around against the Saints to accommodate the former England international. When on-loan from Manchester City last term, Barry flourished in the heart of Everton's midfield. But the 33-year-old has yet to score since making the permanent move to Goodison Park, and seems to be far less effective in the Everton side.

Barry was a huge part of Everton's success in the last campaign, but if the Toffees are going to start climbing the league, he must start replicating his form as soon as possible.