If ever a Premier League manager needed a warning on the pitfalls of splashing the cash in the January transfer window, they need look no further back than a year ago.

Last season, a record £225m was spent overall with Fernando Torres's £50m move from Liverpool to Chelsea helping fund the Reds' purchases of £35m Andy Carroll and £22.7m Luis Suarez.

The Uruguayan striker has easily been the most successful buy from that trio, his eight-match ban for racially abusing Patrice Evra apart, and the three goals scored by Torres and Carroll combined summed up the rest of their seasons at their new employers.

In fact, if you add in Chelsea's £21.3m capture of David Luiz, the two clubs forked out a combined £129m last January yet moved up three Premier League places between them.

This not only goes to show that the mid-season transfer window is a seller's market, but also that the real benefit in this period might actually be for clubs at the other end of the table.

The same year the window was introduced in 2003, Christophe Dugarry scored five goals to help retain Birmingham's Premier League status, while two years later Kieran Richardson did similar for West Brom. And in 2007 David Unsworth left Sheffield United to join Wigan and four months later scored the winning goal that sent the Blades down.

So even if last season, signings like Daniel Sturridge at Bolton and Demba Ba at West Ham only helped their respective teams to initial success before a slide in form, there is plenty to encourage managers as they attempt to bolster their troops and tweak their tactics for the relegation battle ahead.

Wigan have become the benchmark for Premier League survival since being promoted to the top tier in 2005, so much so that current boss Roberto Martinez calls this period the "window of hope".

However, his experience tells him there are specific criteria for what constitutes a good signing during the most competitive time of the year.

"The benefits of the window are that sometimes you know exactly what you need because in January you have a clear idea of where the squad is and what the levels of performance are," he says.

"But the hard part is that, whatever you look for, it is very difficult to find because it's too expensive and clubs are not willing to let players go.

"That means you need to go into markets abroad and bringing in a player in January means that the adaptation period is going to be six to eight weeks and that's probably too long. So you need to bring in players who already have some Premier League experience and that has a real cost.

"It's great for the media and the fans; it's a window of hope. When things are not going well, you think that everything is going to be solved and it is a key moment in the season. In the same way, you have to be realistic that you get good value for money and I don't think you normally can."



Carroll and Torres struggled individually, but even Sturridge and Ba had a limited impact last season

Martinez cites Gary Caldwell as a player who had a big impact when he joined Wigan in January 2010, based on his winning mentality while at Celtic and his knowledge of the British game.

But the Spanish boss also believes Bolivian forward Marcelo Moreno gave a boost to the side the same season thanks to his European experience, and even the signing of Crystal Palace youngster Victor Moses was well-timed as it gave him a period to adapt to the top tier before embarking on a full campaign. It may also mean Wigan pipped a few rivals to his signature.

Moses, 21, has taken time to blossom in the Premier League, but he is not the only one in that bracket. Manchester City spent £27m last season on Edin Dzeko and only following a full pre-season has the price tag begun to look justified.

QPR striker DJ Campbell, who made the leap from League One Brentford to Premier League Birmingham in January 2006 and twice went on loan to Blackpool, says moving in mid-season makes it difficult to adjust.

"When you join in the summer, you've got time to put in a full pre-season and time to get to know the lads," he says. "You also have time to know how the gaffer works and how he wants everyone to play rather than arriving in January and finding out for yourself. So it takes a few games to get into the swing of things.

"It's difficult, especially sometimes when you don't know anyone at the club, but you are a professional and you've just got to handle it as best you can. The other thing to say is that when I joined Birmingham, it was the first time I'd ever played in the Premier League so my adrenaline got me through a lot of things."

Campbell currently finds himself on the other side, his place at QPR seemingly under threat now boss Mark Hughes has been appointed after Neil Warnock's sacking and with the loan signing of Manchester United forward Federico Macheda increasing competition for places.

But rather than see it as a knockback, Campbell, who has been out for two months with a metatarsal injury, believes it is only a good sign as the club tries to avoid the relegation zone.

Speaking before Warnock was fired, he adds: "The situation that we're in at the minute is not good so we welcome players in because we need them. New faces at this time will help.

"When I was at Birmingham, we were struggling a bit at the time and I was fortunate enough to be able to come in and the players welcomed it. You don't look at it like they are trying to pinch your position, it's a team game, so the better players that come in, the better we get."

The loan market has its critics but with the competition to sign players and the elevation of prices as high as it ever has been, it is becoming an increasingly sensible option for cash-strapped clubs.

Uefa's Financial Fair Play initiative also means that the elite end of the Premier League is unlikely to spend as extravagantly as it did last term.

So even if top-flight bosses complain about calls from agents and reporters stalking them when they arrive at training, they will realise that the window of opportunity is all important.

With a new domestic and overseas television deal in the offing and debts to be paid off, the significance of a club's Premier League status is worth a few sleepless nights.

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