Life at Manchester United started sweetly for Eric Bailly.

The first signing of the José Mourinho era – joining in a £30million deal from Villarreal – he wasted no time making an impression at the club.

Of course, he was far from being United’s highest-profile recruit that summer.

During an impressive window, the Red Devils re-signed Paul Pogba from Juventus for a then world-record £89million, snapped up Henrikh Mkhitaryan from Borussia Dortmund and captured Zlatan Ibrahimović, one of the most accomplished strikers of his generation, on a free transfer.

But it was Bailly who stole the show in the first few weeks of the season. Then 22, the centre-back put in back-to-back Man of the Match displays in the Community Shield win over Leicester City and the opening Premier League victory at Bournemouth.

It set the tone for a successful first year at the club. Although a knee injury reduced him to 38 appearances in all competitions, he was named in the Europa League Squad of the Season as United clinched that piece of silverware after having already won the League Cup.

Ibrahimović, who scored 28 goals, and Pogba, who dazzled and frustrated in equal measure, often occupied the back pages but United fans were optimistic about their new defender.

Commanding, aggressive and incredibly mobile, Bailly looked to be the man to finally fill the void left by Nemanja Vidić’s departure (the Serb joined Inter Milan in 2014). A top performer on the pitch and a larger-than-life character off it (not a lot of people, joking or not, would dare to kick Ibrahimović), he was a fan-favourite.

Lately, though, Bailly’s situation, like many of teammates, has darkened. This season started promisingly, too, with an impressive display in August’s 2-1 win over Leicester. Luke Shaw and Pogba scored but Bailly dominated Foxes striker Kelechi Iheanacho throughout and landed a crunching tackle to stop rampaging full-back Ben Chilwell getting into the United box.

Bailly’s next outing was a much more harrowing affair. Paired alongside Victor Lindelöf, the Ivorian struggled with Glenn Murray’s physicality and conceded a penalty when he lunged in recklessly on Pascal Groß. Not only was it a fatal error in judgement, but the defender’s mistake also came just as United threatened to turn the game in their favour after Romelu Lukaku pulled it back to 2-1 following early goals by Murray and Shane Duffy.

Although Lindelöf was also culpable for United’s dismal defeat at the Amex, it was Bailly who lost his place in Mourinho’s squad. The Sweden international dropped to the bench for the visit of Tottenham Hotspur to Old Trafford a week later, but there was no place in the 18-man squad for Bailly, a decision made all the more strange by Mourinho’s decision to play Ander Herrera in a back three. United lost 3-0 and the Basque midfielder lasted less than an hour.

Since then, Bailly has managed 21 minutes of Premier League action. Used as a stoppage-time substitute to run down the clock during victories at Burnley and Watford, a steady performance against Valencia earned him a shot at redemption as Newcastle United came to town four days later.

Paired with Chris Smalling, the 24-year-old’s afternoon ended ignominiously, subbed after 19 minutes having failed to stop the Magpies charging into an early two-goal lead. Mourinho later insisted that the decision was ‘tactical’ but the ease with which Rafa Benítez’s side sliced through the United defence reflected badly on the African. Caught napping for Kenedy’s opener, Bailly then failed to meet Jonjo Shelvey’s cross, allowing Muto to control, turn and smash home the second.

United’s late resurgence salvaged that game but Bailly has not been seen since. Now linked with a move to Arsenal and Spurs, January may spell the end to a United career that once promised so much.

His stats from 2016/17 demonstrate what an effective operator he can be, ranking second in tackles per 90 (2.66), seventh in interceptions (2.62) and seventh in successful take-ons (0.65) among defenders. Under an excellent man-manager like Mauricio Pochettino or Unai Emery, Bailly may be able to breathe new life into his flagging career in English football.

Emery is said to be on the lookout for defenders while Pochettino is braced for Toby Alderweireld’s eventual departure, opening up a potential new home for Bailly in north London.

It’s been evident throughout his time, though, that Bailly requires coaching. Still raw and reckless, his mishap against Brighton proved that he can’t always be trusted, but Mourinho must, too, accept responsibility.

A signing he demanded, it speaks volumes of the manager’s mindset that he would rather pursue another big-money recruit than focus on improving Bailly, especially now as Lindelöf and Shaw appear to be on the right path. Rejuvenating him would be a significant step in cementing the United back-line of the future.

However, having lost both Mourinho’s trust and his own self-confidence it’s looking increasingly likely that Bailly will need to find a new club. As long as Mourinho occupies the touchline, his future at the Theatre of Dreams will more closely resemble a nightmare.

If he leaves, he will go down as one of United’s great unfulfilled talents in recent years.