Manchester United left-back Luke Shaw looks set to leave the club this summer after falling out of favour with manager Jose Mourinho, and has been linked with a £15m move to Newcastle United by the Daily Star if the Magpies win promotion back to the Premier League this season.

Despite seemingly being around for years, the England international is still just 21 years of age and after making just 43 appearances in all competitions for the Red Devils following his move from Southampton in 2014, he looks set to move on to pastures new at the end of the campaign.

Any approach from Rafa Benitez would depend on the Toon Army regaining their top flight status, but they look in pole position to do so as they currently sit at the top of the Championship standings.

While it would appear to be a good addition on paper, some will be wondering why the defender has failed to make the grade at Old Trafford under two separate managers.

Here are THREE reasons Shaw wouldn’t be a good addition for Newcastle…

Fitness

Shaw’s fitness has come into question from former United manager Louis van Gaal, and now current boss Jose Mourinho.

There must be a reason that it hasn’t been considered satisfactory by two successful and experienced managers, and that would certainly be a concern for Rafa Benitez if he was to shell out £15m on the left-back this summer.

His lack of playing time this season certainly won’t have helped him, and it would take a big pre-season to get him in shape and fully fit for a Premier League campaign - a risk that might not be worth taking for a newly--promoted club.

Injury recovery

While so impressive for Southampton and early on in his United career, Shaw has struggled in the last couple of seasons – form which wasn’t helped by the leg break he suffered against Fenerbahce in the Champions League in 2015.

Sometimes players don’t fully recover from serious injuries, and having shown few glimpses of getting back to his best in recent times, Benitez could again be wary of spending £15m on a player that might not get back to his best – both physically and mentally.

Attacking tendencies

One of the main reasons that Newcastle suffered relegation last season was because their defence wasn’t good enough, and Rafa Benitez will want it to be more solid should they make an instant return to the Premier League.

The problem with signing Shaw is that the left-back loves to get forward and support attacks, but it is something that could leave the Magpies short at the back when other teams counter.

The Premier League is a level where you get punished, and whether the 21-year-old would be happy – and comfortable – in what could be a largely defensive role next term remains to be seen.

Do you agree, Newcastle fans? Let us know below.