The 2014-15 Barclays Premier League transactions culminated in numerous big spending deals, bargain buys and potential transfer flops. Already four weeks into the new season, compiled below is a list of the five best and five worst Premier League deals throughout the summer.

Five Best Deals

1. Diego Costa, 25, Forward (Atletico Madrid to Chelsea)

Without a doubt, this must be considered the Premier League signing of the summer. In Costa, Chelsea have finally found a prolific striker. Amassing a total of 36 goals in all competitions for Atletico Madrid last year , Costa has slowly emerged into the spotlight following brief and negligible spells at Albacete, Valladolid and Rayo Vallecano. His lethal two-footed shooting ability as well as his imposing presence have already resulted in seven goals in only four appearances for the Spaniard. Chelsea have struggled in recent years to find a consistent striker but seem to have found the perfect fit with Costa. A great work ethic coupled with clinical finishing, Costa can prove to be the difference in Chelsea’s title aspirations.

2. Gylfi Sigurðsson, 25, Midfielder (Tottenham Hotspur to Swansea City)

Returning to Swansea following an unsuccessful spell at Tottenham Hotspur, Sigurðsson has quickly settled into his new club, spearheading Swansea’s victories over Manchester United and Burnley. Valued at around £10 million, Sigurðsson can serve as the creative focal point for Swansea this year, playing alongside a perilous attack consisting of Nathan Dyer, Wayne Routledge and Wilfried Bony. Sigurðsson’s recent performances both internationally and at club-level have placed question marks over Spurs impetuous decision to let him return to a club where he made a significant impact while on loan almost four years ago. The Iceland international can provide a polished passing dimension that the Swans certainly lacked last year.

3. Alexis Sánchez, 25, Forward (Barcelona to Arsenal)

An immense addition no doubt, Sánchez’s arrival at Arsenal is a testament to their pursuing Premier League title ambitions. Twelve months after the addition of Mesut Ozil for a club record transfer of £42.5 million, Arsenal have yet again flexed their financial muscles with a £35 million move for Chile’s star forward Sánchez from Barcelona. Having scored two goals for his national side in the World Cup, Sánchez’s versatility up front will prove to be a nightmare for Premier League defenders. Offering natural width as well as an innate goal-scoring ability, Sánchez could prove to be the final piece in Arsene Wenger’s title jigsaw.

4. Cesc Fàbregas, 27, Midfielder (Barcelona to Chelsea)

How Chelsea managed to secure Fàbregas’ services for such a low price tag (£30 million) considering his past successes at Barcelona remains in question. Solidifying Chelsea’s midfield alongside a robust Nemanja Matic, Fàbregas’ versatile playing style offers Chelsea options both offensively and defensively. His previous experiences in the Premier League at Arsenal will no doubt result in a smooth transition for the 27-year-old Spaniard. Chelsea’s midfield will definitely be a force to be reckoned with throughout the 2014-15 Premier League campaign.

5. Ángel Di María, 26, Midfielder (Real Madrid to Manchester United)

Heavily linked with a move away from Real Madrid throughout the summer, Ángel Di María’s arrival at Manchester United came as bit of a surprise for everyone. The Argentine’s move from Real Madrid broke the British transfer record with a suspected fee of £59.7 million. Following a marvelous performance in Argentina’s 4-2 win in Germany last week, Di María has instigated a surge of excitement throughout the Premier League. Last season alone, the Argentine contributed 17 assists for his club side, more than any other player in La Liga. Manchester United manager Louis Van Gaal recently bemoaned the lack of creativity emancipating from his side, surely Di María’s technical prowess will provide the results the red devils need to secure a top four finish this year.

Five Worst Deals

1. Shane Long, 27, Forward (Hull City to Southampton)

Following a brief and somewhat uninspiring spell at Hull City, Shane Long’s surprising £12 million transfer to Southampton remains a staggering transaction, considering Long has never managed to score past double digits in a Premier League season. Reaching the latter stages of his footballing career, Long’s price tag is a clear departure from his below par performances on the football pitch. There have been sparks of brilliance from the Irishman, including his solo performance against Aston Villa last year, but Long’s inconsistencies overwhelm any hopes of him becoming Southampton’s top goalscorer.

2. Sandro Raniere, 25, Midfielder (Tottenham Hotspur to Queens Park Rangers)

Failing to prove his worth during his time at Tottenham, Sandro has been given a chance to redeem his previous shortcomings. Reunited with former manager Harry Redknapp who initially signed him to Tottenham from Internacional in 2010, Sandro’s £2 million increase in price comes as a bit of a surprise, considering the fact that he averaged just below 20 games a season for Tottenham. The 25-year-old defensive midfielder needs to become an integral piece in Redknapp’s newly-promoted Queens Park Rangers side if he is to convince anyone of his hefty £10 million price tag.

3. Luke Shaw, 19, Defender (Southampton to Manchester United)

An integral wing back for Southampton during the 2013-14 campaign, Luke Shaw’s relative inexperience and formidable price tag of £32 million might prove to be too big of a gamble by Manchester United manager Louis Van Gaal. After missing the first three competitive games due to a hamstring injury, Shaw will be eager to demonstrate what he is capable of. Currently the fourth most expensive defender of all time, Shaw’s starting place in the squad may already be in question considering United’s recent purchases of Daley Blind from AFC Ajax and Marcos Rojo from Sporting Lisbon.

4. Eliaquim Mangala, 23, Defender (Porto to Manchester City)

Manchester City’s new £32 million signing from Porto, Eliaquim Mangala, has not been guaranteed a starting place at his new club. Preferring the likes of Martin Demichelis and Vincent Kompany as his two center halves, Manuel Pellegrini’s recent new addition remains contentious. Considering that Mangala has never played in one of Europe’s “big five” leagues, the French international may face an uphill challenge with breaking into the first team line-up. Given an extended rest for his participation in the World Cup, Mangala should be poised for his Manchester City debut in the near future.

5. Adam Lallana, 26, Midfielder (Southampton to Liverpool)

Despite being one of last year’s Premier League standout players and earning a place in England’s World Cup squad, Adam Lallana’s £25 million departure from St. Mary’s after eight years of service must be viewed as nothing other than a bargain for Southampton. Part of Southampton’s summer exodus, Lallana’s starting place on the team may have been jeopardized following Liverpool manager Brendan Rodger’s decision to add striker Mario Balotelli to the club’s attacking force. Possibly employing Daniel Sturridge and Raheem Sterling on the wings, Rodgers will have to reconsider Lallana’s future role on the team.