Former Newcastle United owner Mike Ashley remains a deeply unpopular figure at St James' Park, with the much-maligned businessman having overseen a dismal spell at the helm for well over a decade, prior to his long-awaited departure back in 2021.

That turbulent and toxic period - in which the club suffered two relegations from the Premier League - seemingly saw the Englishman make notable blunders with regard to recruitment, in particular, having done little to truly contribute to on-field success.

One potential howler that the 58-year-old did endure was the sale of Congolese defender, Chancel Mbemba, with the commanding centre-back having since gone on to blossom following his departure back in 2018.

The former Anderlecht man had initially been snapped up on an £8m deal by the Magpies in the summer of 2015, going on to rack up 59 appearances in all competitions over the next few years.

While the 6-foot brute was arguably not a huge success on Tyneside - having looked "out of sorts" at one stage, according to club legend Alan Shearer - it does appear to have been a mistake not to have persisted with him, such has been the 65-cap titan's displays then.

It also appears an error not to have recouped a greater fee with the player's eventual sale to Primeira Liga outfit, Porto, as Ashley and co reportedly raked in around €8m (£7m) - a slight loss on their initial investment.

That figure has now been dwarfed by the 28-year-old's current value, with the Marseille man said to be worth in the region €25m (£22m), according to CIES Football Observatory, ensuring he is now valued at around three times what the northeast side were able to sell him for.

After spending four seasons in Portugal - in which he racked up 138 appearances in all competitions and won two league titles - Mbemba is now continuing to thrive in France, after making the move to the Stade Velodrome during the summer.

That free transfer switch already appears something of a bargain for the Ligue 1 outfit, with the "formidable" rock - as recently described by ex-Newcastle teammate Henri Saivet - having already scored four times and provided one assist in 29 games in all competitions this season.

A leading figure in Igor Tudor's side, the £87k-per-week powerhouse has averaged 1.2 tackles and 1.3 interceptions per game from his 22 league outings, with that in fact a better record than current Magpies star, Sven Botman, who has averaged 1.1 and 0.8 for the same two metrics, respectively, from his 19 top-flight appearances.

Mbemba also compares favourably to those in his position in Europe, as he ranks in the top 4% for progressive carries and the top 9% for progressive passes among his peers, illustrating his brilliance in possession.

With Eddie Howe and co likely to be pursuing a new central defender in the near future due to the lack of depth outside of Botman and Fabian Schar, it may be of real frustration that one of the club's former assets is now impressing elsewhere.