For every up Phil Jones has experienced during his Manchester United career, it has invariably been followed by a down.

Down on the floor, usually, clutching an ankle or a foot. And then facedown on a treatment table, sometimes for weeks. Occasionally for months.

It is the story of Jones' six and a bit years at Old Trafford that periods of impressive form have often been halted by injury. Sometimes niggly ones, sometimes more serious.

Since arriving from Blackburn for £16.5 million in 2011, he has been sidelined 31 times, either through injury or illness. Since the start of the 2015-16 season alone, he has suffered six different injuries accounting for 261 days out and missing 56 games.

It says a lot that Jones has made 174 appearances for United, just 20 more than Juan Mata, who joined the club from Chelsea two and a half seasons later.

Jones, not for the first time, is enjoying a good run. He has started all six Premier League games for Jose Mourinho's side this season, helping to keep clean sheets in five. His only blip came in the 2-2 draw at Stoke, after which former teammate Rio Ferdinand -- an idol growing up -- criticised his defending for Maxim Choupo-Moting's first goal.

Choupo-Moting lost Jones at a corner for Stoke's second goal, too, prompting Mourinho to say afterwards "he knows the mistake" before leaving it at that. Mourinho said later he did not "kill" Jones for the error, but sources have told ESPN FC that he was left in no uncertain terms in the away dressing room at the bet365 Stadium that it should not be allowed to happen again.

Whatever was said, it seems to have worked. Two more clean sheets, against Everton and Southampton, have followed. Jones, again alongside Eric Bailly, was particularly impressive at St Mary's. No United defender made more tackles, clearances or blocks, meaning that, in a game Southampton dominated in the second half, David De Gea did not have a meaningful save to make.

Mourinho admitted in his postmatch news conference that his team had needed the central defenders to be "very good."

The worry, though, with Jones is that another injury could always be around the corner. As United were being linked with centre-backs Mats Hummels and Stefan De Vrij during the summer of 2014, United's medical staff told new manager Louis van Gaal that their data suggested Jones was on course for an injury-free season.

But he would go on to make just 24 appearances in all competitions. The following season it was even fewer -- 10 Premier League appearances, 13 in total.

There has always been hope at Old Trafford that Jones, eventually, would have a change of luck. While persistent muscle injuries are red flags to a medical department, many of Jones' problems were down to freak accidents or misfortune. During preseason training in 2015, he was diagnosed with a blood clot after complaining of a tight calf. He was given blood thinning tablets and missed the first nine games of the season.

Phil Jones has suffered an injury-hit career at Manchester United but is once again back in form and favour. Paul Jenkins/Action Plus via Getty Images

Typically of Jones, he had finished the previous season well, starting seven of United's last 10 games, including impressive wins over Tottenham, Liverpool and Manchester City.

United's staff say part of the problem -- if you can call it that -- is that he trains the way he plays. After winning back his place in the United team in March last season, Jones went into a challenge with Chris Smalling during an England training session and came away with a broken toe that ruled him out for 10 games.

In 2013, Wayne Rooney needed 10 stitches in a head wound after an accidental clash with Jones at Carrington. Jones, according to those who know him best, has never been one to believe his natural talent allows him to coast through training.

His football career started at Ribble Wanderers Juniors, but only because he could not get a game for another team. Less than a year before making his first team debut for Blackburn as a 17-year-old, he was dropped by their youth team. His youth team coaches talk about a player who was never head and shoulders above the rest but one who had the determination and worth ethic to make up the difference.

It is an attitude that has helped win over Mourinho, and Jones, now 25, is back as a regular for both United and England.

It has given him cause of optimism that he will be part of Gareth Southgate's England squad for the World Cup in Russia next summer, preferably with another Premier League winners' medal in his pocket. He can only hope his body doesn't have other ideas.