Why do teams have a 'bomb squad'?

Raheem Sterling spent 18 months as a member of Chelsea's so-called 'bomb squad' before agreeing to end his contract by mutual consent.

The England international, 31, had not played a competitive game for the London side since May 2024 and no longer trained with the first-team squad, with no realistic prospect of selection for matches.

His Chelsea team-mate Axel Disasi was also frozen out and made to train with both the Under-21s and the 'bomb squad' before the arrival of Liam Rosenior.

But why is this approach adopted by some clubs - and how can it affect players?

Though not an official term, in football 'bomb squad' is widely used to describe players who have fallen out of favour but still remain under contact.

Those players are often excluded from first-team training and have to attend separate sessions with the club's youth teams, or even on their own in extreme cases.

Some clubs even go as far as restricting any contact between the first-team and 'bomb squad' members by scheduling training sessions at times of day that will minimise the crossover between players.

Others also arrange training exercises at completely separate facilities.

Former Manchester City and Real Salt Lake defender Nedum Onuoha told the BBC's More than the Score podcast his time as a member of City's bomb squad was "the toughest stretch" of a career that featured injuries and relegation battles.

Onuoha found himself out of the first team during Roberto Mancini's tenure at City, receiving a text message telling him not to attend the club's first-team training.

He and a number of other players were to instead train with City's Under-16s and Under-18s and miss out on the club's tour of the United States.

"When you hear that someone isn't allowed to train with the first team, you tend to believe it's for disciplinary reasons... that's something I never was," he said.

"You find yourself trapped in a position where you are nowhere near doing the thing which you love."

He says that when the regular team returned from the US, he and fellow bomb squad team-mate Craig Bellamy went to watch the end of one of their training sessions on an adjacent pitch.

That evening, Onuoha received a text telling them they could now only come to the training ground from 3pm onward - the latest time anyone in the first team would still be present.

Onuoha says the entire period "really affected" him.

"You are so far away from the dream you had as a child... I kept thinking, why is this happening?" he said.

Contractual complications are usually the reasons that players find themselves stranded in a club where they are not playing with the first team, but can't leave.

There are strict regulations implemented by Fifa that mean there can be no 'abusive conduct' by the club isolating players - including those in the bomb squad - from the first team, which may entitle a player to terminate their contract citing 'just cause'.

Former Chelsea manager Enzo Maresca made headlines by comparing Chelsea's bomb squad to his father's job as a fisherman.

Aberdeen Sporting Director Lutz Pfannenstiel told the BBC World Service that he personally would not treat bomb squad players so harshly, but could also see why teams decide to implement such measures.

"Maybe the club is too big, maybe the manger fancies someone else... there are different reasons why a players isn't part of the club's plans any more," he said.

"Is there a better way to handle it? Sure, straight away go to the agent, pay out the player, terminate the contract, shake hands, smile, hug each other. But that's a fairytale."

He also said there may be discussions taking place around the player's future that they are not privy to.

"Lots of times clubs will find a pretty quick situations with loans or sales or finding ways to make it work for player. But there are isolated cases where the agent of a player makes it very difficult. Players don't always hear the discussion with sporting director where you feel only ways to keep the player and keep them fit."

Being relegated from the first-team squad does not necessarily spell the end of a player's competitive career.

Marcus Rashford has flourished since being sidelined by Ruben Amorim at Manchester United, scoring four goals and making six assists on loan at Aston Villa.

He has since been loaned to Barcelona where he has scored nine goals and made 12 assists in 31 appearances.

His former United team-mate Alejandro Garnacho, also sidelined under Amorim, later transferred to Chelsea.

Despite the negative press, Onuoha says bomb squads won't be disappearing.

"When I was playing there was a rule as such within the Professional Football Association that as long as there was a minimum amount [of players] involved in training sessions, the union won't get involved, so teams will use that as a go-around.

"For those that go through it, I hope they can find the support to get through what for many, like myself, is probably the toughest time in their career."

This article is the latest from BBC Sport's Ask Me Anything team.