Chelsea will lurch from one manager to the next until such a time they can create a strong backbone to their squad.

The decline of John Terry is likely to see the final player from that core group of players leave the club as they have done over the past 15 months.

Frank Lampard was the first to leave in 2014 with the returning Didier Drogba and Petr Cech departing in the summer of 2015.

With them went the 'Mourinho' voices in the dressing room, leaving Terry as the remnant from that Chelsea generation with squad player John Obi Mikel.

On current form, it would appear that Terry, 35, is unlikely to earn another new deal and Mikel is also likely to depart in 2016.

But, the question is, which players will step up to fill those voids?

The teams that sustain greatness over a period of time generally have a spine of players (goalkeeper, centre back, central midfielder, striker) who rattle straight off the tongue.

For Chelsea, it was Petr Cech, Terry, Frank Lampard, Didier Drogba as the team straight down the middle from back to front.

Arsenal had Jens Lehmann, Sol Campbell, Patrick Vieira, and Thierry Henry when they became the Invincibles. Manchester City have Joe Hart, Vincent Kompany, Yaya Toure and Sergio Aguero.

Old guard: Petr Cech, Frank Lampard and Didier Drogba celebrate with the FA Cup

On the continent, the legendary Barcelona team had a core Victor Valdes, Carles Puyol, Xavi, Andres Iniesta and, of course, Lionel Messi.

Manchester United's long period of success will forever be linked with the Class of 92 that saw a group of players come through in defence and midfield, which is unlikely to be repeated. Pairing them with Peter Schmeichel, Edwin Van Der Sar, Andy Cole, Cristiano Ronaldo et all made them a force for around 15 years.

When you compliment those teams with talented players on the flanks like Juan Mata, Ashley Cole, Pablo Zabaleta, Robert Pires and others the team will always be there or thereabouts when it comes to competing for trophies.

Where will Chelsea's next spine come from? Thibaut Courtois is a given, provided he stays, but what about the other three?

Gary Cahill is a senior player now but finds his position in the side under threat from Kurt Zouma.

Cesc Fabregas' form has been atrocious this season, while Eden Hazard, rumoured to be leaving the club, and Nemanja Matic has been off-colour as well suggesting a leadership role in the dressing room may not be for them. Willian has impressed this season but his role out wide sees him complimenting the spine, not being a part of it.

Up front, Diego Costa has worn the patience of Chelsea fans with his antics, Loic Remy is a good squad player, while the less said about Radamel Falcao the better.

Jose Mourinho's two stints at Chelsea in pictures:

Manchester United have slipped back because they have lost their core players through retirement, sales or age and Chelsea have done the same.

The next Chelsea boss will have to conduct major surgery on the squad to try and bring in a spine, meaning the Roman Abramovich chequebook will be required. It's reached the point of 'start again'.

The Russian, as he has shown in his 11 years at the helm of Chelsea, is ruthless when it comes to his ambition for success and won't accept anything less.

As has happened with every appointment, not just at Stamford Bridge but with virtually every club in the country, a new manager will come in and talk about the long-term in his first press conferences and how they want to build the club for the next 10 years. However, he will know the score just as you or I do – bring success or you're sacked.

Because the Blues squad is in need of major surgery to bring about the next generation of captains, leaders and legends the latter will happen more often than not until the body of the team is stitched up and ready to have a sustained run of success again. Buckle up Chelsea fans, the next few years are likely to be a rollercoaster.