Of Stoke's out-and-out strikers, John Carew is the only one to have scored since their FA Cup third round draw with Cardiff way back on 8 January.

That may give Potters boss Tony Pulis food for thought ahead of his team's cup quarter-final at home to West Ham on Sunday, especially as Hammers forward Demba Ba looked like he would join Stoke in January before failing a medical.

Since then Stoke's loss has certainly been West Ham's gain as the Senegalese striker has inspired his new team to greater heights, putting them within touching distance of a return to Wembley for manager Avram Grant and boosting their Premier League survival hopes no end.

Even from the outset, when the former Hoffenheim player came on to make his debut in the 1-0 defeat by Birmingham, he injected an energy which almost instantly paid off when he crashed a shot against the post.

The statistics following that game have been startling. Not only has Ba notched four goals in his four starts, but he has helped the Hammers score 14 goals in that period, including the 3-0 Premier League win over Stoke last weekend.

That is not just fortune. Since Ba's arrival West Ham have increased their average number of shots on target in Premier League games from 37% to 49%.

And even that stems from an improvement in average ball possession, up from 44% to 52%, with pass completion in the opposition half also increasing from 66% to 73%.

West Ham's progress is not all down to the 25-year-old, of course.

The re-emergence of Thomas Hitzlsperger has added ballast and an attacking threat to the midfield, with Grant saying the 28-year-old is almost like a new signing, having been out for so long with a thigh injury.

The former Aston Villa player, who possesses a hammer shot and has mustered two goals in three games, has also has given Grant the option to pick a 4-3-3 formation with added balance.

Average positions from the 1-0 defeat by Birmingham and last Saturday's victory over Stoke show the difference in playing Hitzlsperger (11) alongside Scott Parker (8) and Mark Noble (16) instead of Gary O'Neil (32).

By selecting a three man midfield, which includes the German, Grant can pick an extra forward and give strength to the left side where the Hammers have been sometimes exposed earlier this season.

During the Birmingham game where Ba made his debut, the problem was evident when West Ham started with a front three of Victor Obinna, Robbie Keane and Frederic Piquionne with Parker, Noble and O'Neil in midfield.

Pass patterns from that game show the midfield trio tended to occupy spaces on the right, leaving Obinna with a lack of support on the other side of the field.

And even though it did not stop the Nigerian playing well, it is only when you look at the passes from Hitzlsperger in the Stoke game last week where you can spot the difference.

The German's pass map shows that while he is a busy midfielder, many of the spaces he occupies are on the left from where he completed 90% of his passes, with an assist and a goal to boot.

His positioning also gives Wayne Bridge extra cover, which is something the left-back has needed since making a bad start to his time at Upton Park. Bridge's average positions in recent games show he is getting forward more often as a result.

Stoke, meanwhile, have the chance to re-enact some measure of revenge against West Ham on Sunday while aiming to reach the FA Cup semi-finals for the first time since 1972.

In contrast to their rotten away form - they have lost their last six Premier League games on the road - the Potters are unbeaten at the Britannia Stadium in 2011.

Pulis has recently been more inclined to play two strikers at home, opting for a lone forward on his team's travels, which might partly explain the lack of goals from his forwards.

But there may have been an added factor - namely the absence of Matthew Etherington, who has been suffering from a back injury.

The left-sided midfielder looks set to face his former club on Sunday and his inclusion will be welcomed by Pulis and Stoke fans based on his Premier League record since joining the Potters in January 2009.

Although the 29-year-old has not missed many games since his move from Upton Park, it is clear Etherington complements Jermaine Pennant on the right.

So he may be able to provide opportunities for Stoke strikers Kenwyne Jones and Ricardo Fuller so that they can help Carew on the goalscoring front.

At the same it might also put any regrets Pulis has about not signing Ba to the back of his mind.

Will Etherington make a difference for Stoke or are there wider problems? And what about West Ham, has the impact of Ba and Hitzlsperger been as marked as it appears?

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