Chelsea recently made a £20 million offer for centre-back John Stones which Everton immediately refused with Roberto Martinez stating he would not sell the defender for double that amount.

However, despite the youngster’s claims that he is happy at Goodison Park, he or rather, Martinez could most likely be persuaded to join the Blues for the right fee.

Here are five reasons why Jose Mourinho should meet that fee:

Has shown potential to be one of England’s best

The 21-year-old signed with Everton from Barnsley for £3 million in 2013. He started 23 of Everton’s 38 games in the 2014-15 season, becoming Phil Jagielka’s regular partner at centre-back just one year after joining the club.

Even at his young age, Stones has shown quality and composure characteristic of world-class defenders. He has intelligence in tough situations that managers want in front of goal.

England Under-21 boss Gareth Southgate has said of Stones, “He’s the type of player that, were he Portuguese and German, we’d be saying, ‘why can’t we produce players like that?'”

Indeed, if Mourinho can manage to sign the youngster, he could develop alongside Mourinho and John Terry into one of England’s finest centre-backs.

Gary Cahill’s inconsistency

In his three years at Chelsea, Gary Cahill has won every honour with the club and established himself as Terry’s partner in the centre of defence.

However, after Chelsea’s 5-3 defeat to Tottenham Hotspur on New Year’s Day, Cahill was dropped in favour of Kurt Zouma for domestic matches against Manchester City, Everton, and Burnley as well as the Capital One Cup semi-final second leg against Liverpool.

In January, it looked as if the 29-year-old’s future at Stamford Bridge was in question as 20-year-old Kurt Zouma impressed in defence. Mourinho did restore him to the starting lineup for the Capital One Cup final against Tottenham though, and the Englishman continued to be a regular starter alongside Terry for the rest of the season.

However, Cahill will turn thirty this year, and as he was inconsistent in the last season, it is likely that his form is beginning to decline. Zouma has already proven that he can challenge Cahill for his starting position, and the 20-year-old seems poised to dislodge the older man as the starting left side centre-back within a few years.

Terry, Cahill, and Zouma are currently the only central defenders on the first team, and Zouma seems set to send Cahill to the bench relatively soon. It would make sense for Mourinho to sign another centre-back such as Stones to challenge Terry and Zouma if Cahill finds himself playing backup to the latter.

Replace the ageing John Terry

Terry, who has been with the club since he was 14, is a hero to Chelsea fans for his loyalty and his leadership. The Chelsea captain played every minute of the 2014-15 campaign.

He also scored five goals last season to become the Premier League’s all-time highest scoring defender with 39 goals, performing excellently over the course of the season with no signs of slowing down.

Of course, it is understood that there will come a time when Terry will slow down, and that time may not be far off. The 34-year-old centre-back is not getting any younger.

Terry renewed his contract with Chelsea for one year last season, which is the Blues’ policy for players over the age of 30, but who knows how many more one-year contracts he’ll sign with the club? He has already retired from international football.

It is unreasonable to think that the Englishman will be able to go another entire season without a break. With Kurt Zouma already challenging Gary Cahill’s spot in the first-team, Mourinho would do well to find another centre-half to not only fill in for Terry when he needs rest but to eventually succeed him.

Could form strong, long-term partnership with Kurt Zouma

As previously stated, John Terry most likely does not have very many years left for him at Stamford Bridge, and Cahill has already found his spot in the first-team challenged by much younger Zouma.

If Stones joins Chelsea, it is possible that he could find himself playing regular first-team football next to Zouma within his first several years at the club.

Zouma is a formidable presence in Chelsea’s back line who is constantly improving under Mourinho while Stones is impressive young talent with the potential for greatness.

The partnership that would form between the two is a mouthwatering prospect that could last a decade – Mourinho simply should not pass up the chance to make it happen.

Young player who could spend many years with Chelsea

Finally, the English youngster could be a tremendous signing for years to come.

At 21 years of age, Stones has already displayed considerable potential. If Chelsea were to procure this young talent, he could develop under Mourinho during the peak of his career, easily devoting a decade of service to the Blues.

Stones could be an excellent long-term signing (and not to mention, a player who would count as a homegrown player), continuing to develop his form even after Terry and Cahill end their careers at Stamford Bridge.

The positives outweigh the negatives even if Mourinho would have to pay over the odds for his services.