Luis Diaz and Bruno Guimaraes prove Manchester United made a huge January transfer window error

It was clear from very early on this season that there were a number of gaping holes in the Manchester United squad. And by the time Ole Gunnar Solskjaer had been sacked, hopes of a title charge and even a comfortable finish in the top four were looking ambitious at best.

Champions League qualification was the task handed to Ralf Rangnick when he became interim manager, so you'd have expected some sort of investment to be made in the January transfer window. There were no incoming, only outgoings, meaning United finished the window even weaker than when it first opened.

It's not difficult to see why United would have been so hesitant to splash the cash in January. With a temporary manager at the helm, any big-money signings could soon be deemed surplus to requirements once a permanent manager was appointed. But by taking this approach, the club missed out on the chance to guarantee Champions League football next season.

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United are somehow still in the race for the top four, thanks mainly to the sides around them looking equally fragile. Arsenal, Tottenham Hotspur and even Chelsea have suffered poor results which have kept Rangnick's men within touching distance of the top four, but could one or two new signings in January have given them the edge they needed?

When you look at the impact made by some of the Premier League's January additions, it's clear to see United have missed a trick. The winter transfer window is a notoriously tough time to do good business and is seen more as a chance to make emergency signings, but this year saw a number of quality additions made.

Luis Diaz was brought in by Liverpool and has slotted into