The past four seasons have been a rollercoaster for Chelsea, finishing first, 10th, first again and then fifth during that time.

While a spell of two titles in four years is not to be scoffed at - particularly when no club has retained the title in the past 10 seasons - the campaigns in between their title triumphs have been thoroughly disappointing.

There have been warning signs on both occasions though, from a lacklustre pre-season and the infamous Jose Mourinho vs. Eva Carneiro spat in the opening match of 2015-16 to Antonio Conte's grumblings to the board and decision to sell Diego Costa - top scorer in each of Chelsea's three previous campaigns - prior to last term.

It could be argued that similar signs have cropped up this summer; the sacking of Conte and subsequent arrival of Maurizio Sarri dragged on longer than anyone at the club would have liked, while much of the transfer window was spent discussing potential high-profile outgoings rather than incomings.

However, Sarri impressed during his time with Napoli and owner Roman Abramovich proved that he is still interested by shelling out a world-record sum for goalkeeper Kepa Arrizabalaga, so there are plenty of reasons to be positive for the Blues too.

Here, Sports Mole looks at how Chelsea could line up in the 2018-19 season.

Transfers out: Mitchell Beeney (released), Matej Delac (released), Trevoh Chalobah (loan, Ipswich Town), Nathan Baxter (loan, Yeovil Town), Dujon Sterling (loan, Coventry City), Reece James (loan, Wigan Athletic), Lewis Baker (loan, Leeds United), Jake Clarke-Salter (loan, Vitesse), Jordan Houghton (free, MK Dons), Kenedy (loan, Newcastle United), Jamal Blackman (loan, Leeds United), Todd Kane (loan, Hull City), Mason Mount (loan, Derby County), Charlie Colkett (loan, Shrewsbury Town), Jacob Maddox (loan, Cheltenham Town), Kasey Palmer (loan, Blackburn Rovers), Fikayo Tomori (loan, Derby County), Thibaut Courtois (£35m, Real Madrid), Jay Dasilva (loan, Bristol City)

Much was made of Liverpool's decision to break the world-record fee for a goalkeeper in signing Alisson Becker, but that marker lasted for only a couple of weeks before Chelsea weighed in and brought Kepa Arrizabalaga to the club on the penultimate day of the transfer window. Thibaut Courtois's replacement arrives with a growing reputation and, having signed a seven-year deal, the 23-year-old could become the base off which the next era of Chelsea is built.

One of the main differences at Chelsea this season will be the formation. Conte's 3-4-3 system revolutionised English football in a way that few others have in recent years, but Sarri favours a 4-3-3 system which could see the ever-consistent Cesar Azpilicueta switch back to a wider role, which would in turn likely mean less game time for Victor Moses.

There are big decisions to make in central defence too, with the likes of Gary Cahill and David Luiz eager to impress under the new manager. Antonio Rudiger appears to be the one certain central defensive starter, while Andreas Christensen will be hoping to build on his promising debut season. The left-back slot seems more certain given Marcos Alonso's form in recent seasons, although he may not have as much licence to go forward as he did while playing as a wing-back.

World Cup winner N'Golo Kante will continue to be one of the first names on the teamsheet, while the summer signing of Jorginho should significantly strengthen that area of the field. Sarri knows him well from Napoli and Chelsea stole him from under the noses of champions Manchester City.

The final central midfield spot is up for grabs and there is no shortage of competition for it, with new loanee signing Mateo Kovacic joining the likes of Cesc Fabregas, Tiemoue Bakayoko, Danny Drinkwater, Ross Barkley and Ruben Loftus-Cheek as potential occupants.

Questions also remain over who will lead the line for Chelsea this season, with Alvaro Morata still being linked with a move away - although it is unlikely that Sarri would sanction such a move having missed out on a replacement. Olivier Giroud and Pedro provide further options through the middle, although the latter is more likely to duke it out with Willian for a wider role in the team.

Despite the world-record sum paid for Kepa and the coup of signing Jorginho, Chelsea's best piece of business this summer could well be keeping Eden Hazard at the club - if indeed the Belgian resists the advances of Real Madrid beyond the end of the month. The 27-year-old has scored at least 17 goals in four of the last five seasons and remains the jewel in Chelsea's crown.