Newcastle United's failure to keep Spanish midfielder Mikel Merino at the club remains one of the more perplexing decisions of recent years, with the playmaker having spent just a solitary season at St James' Park before moving on to pastures new.

The then-youngster was lauded as a "quality" addition by Rafa Benitez following his arrival on a season-long loan deal in the summer of 2017, with the club quickly moving to make that switch permanent just a few months later following what was a bright start to life in England.

The former Borussia Dortmund man had notably been compared to compatriot Xabi Alonso by the Magpies boss for his composed displays in the centre of the park, with it looking like he could become a firm fixture for the northeast side for years to come.

As it proved, however, the Pamplona-born starlet ultimately went on to make just 25 appearances in all competitions during that 2017/18 campaign, with a back injury seemingly hampering his progress in the second half of the season.

The 6 foot 2 menace subsequently made a return to his homeland in order to join Real Sociedad, with the La Liga side reportedly capitalising on a £10m release clause in the player's contract in order to bring him back to Spain.

Quite why that fee was so low for a player of such talent remains to be seen, with the 11-cap wonder having since gone on to sparkle following his departure from the Premier League, with his valuation now said to be around £45m, according to Transfermarkt.

Equally, the 26-year-old also appears the type of player who could well have thrived under current boss Eddie Howe, with the 44-year-old currently short of midfield options having unsuccessfully sought new recruits in the recent window.

The £67k-per-week sensation would have added obvious quality having been dubbed the "best player in La Liga" by Sociedad coach Imanol Alguacil in recent times, having scored 16 goals and laid on 19 assists in 162 games for the Basque outfit to date.

It is his quality as a defensive screen in front of the back four that has particularly caught the eye, however, as he notably ranks in the top 3% for aerial duels won among those in his position across Europe's top five leagues, as well as in at least the top 12% for both blocks made and clearances.

An imposing presence in the centre of the park, Merino could well have filled a void in Howe's current squad, with Newcastle seemingly lacking a true defensive-minded presence after missing out on the likes of Edson Alvarez and Ibrahim Sangare over the summer.

If the Spain international was still at St James' Park, he would not only further bolster the midfield options, but could also free up January arrival Bruno Guimaraes to take on a more dynamic box-to-box role, with that seemingly his favoured midfield berth.

The statistics seemingly showcase the Brazilian's willingness to get forward as he ranks in the top 7% for progressive carries and the top 11% for dribbles completed, while he also ranks in the top 8% for pressures made, illustrating his desire to get in the face of the opposition and break up play.

As such, having a calming presence like Merino in the side could well have provided the former Lyon man with a greater licence to impact play at both ends of the pitch, with the Magpies likely ruing their previous failure to keep hold of the one-time Osasuna man for longer than a single season.