1 Player Manchester United Will Regret Not Buying in 2015 Summer Transfer Window

Manchester United were linked with so many players that could benefit the current squad during the summer of 2015 that picking one is a huge challenge.

Many of the players linked with were of the very highest calibre. Gareth Bale and Thomas Muller were two names which came up a lot. Real Madrid president Florentino Perez has said United never made a firm bid for Bale, though they had "expressed interest" in the Welshman, in an interview with Spanish radio station Cadena Ser (h/t the Daily Express). 

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Bayern Munich's president Karl-Heinz Rummenigge said the club had rejected a "huge" offer for Muller during the summer, believed to be from United, per Alex Richards of the Mirror.

Those two are probably the dream signings for United. Bale would have added tremendous pace, power and invention to the Red Devils' ailing flanks. Muller...well, Muller would have been just about perfect—something I wrote about back at the beginning of July. 

It is hard to say that United will "regret" not signing either of those players, given that it was apparently not an option. Mats Hummels is another player who reportedly fits into that category, having decided to stay at Borussia Dortmund rather than move to Manchester, per Marcus Christenson of the Guardian. 

Several other transfers vie for top spot in the regret stakes. Nicolas Otamendi's move to Manchester City could garner a few jealous glances throughout the season, especially if Chris Smalling picks up an injury or two.

Samuel Luckhurst of Manchester Evening News reported that United, "apparently baulked at Borussia Dortmund's £60 million asking price for Marco Reus, whom they attempted to sign as part of Adnan Januzaj's loan move."

Baulking at that price, while paying a fortune for Anthony Martial is difficult to understand given how natural a fit Reus would appear to be for Louis van Gaal's system. A creative wide-attacking player, proven at an elite level. That sounds like something United are crying out for.

However, Reus cannot take the prize of biggest regret, because if reports are to be believed, the clubs' respective valuations were a long way out. The winner by a head in the Manchester United Summer Transfer Window Regret Stakes is Pedro.

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United's failure to sign the Barcelona man, who once played so well against them in the 2011 Champions League final is absolutely baffling for an outsider.

Of course, writing from the sidelines means you are not possessed of all the facts of the case, but the facts that are visible seem to suggest that United could have signed Pedro, but they did not get their house in order to do so.

The player himself told Marca, (h/t Sky Sports)

"

It's true that I don't like that treatment for my colleagues, especially for Victor, who has been a reference as a team-mate and as a professional. I don't believe it's fair but it didn't influence my decision. I just saw that Manchester didn't take that move forward, that they were taking too long. Chelsea were more decisive.

I spoke to Victor a lot. He told me that United was very good and there was a great fan following, but that his only problem was the situation with the coach.

But Victor absolutely did not recommend against signing for United. He spoke very well of the club. It's a great club but I'm convinced I have made the right choice to join Chelsea.

I had an important chat with Jose Mourinho and he said many things that I liked to hear. That, combined with the possibility to live in London, was what made me decide.

"

The key part of that comes in the first paragraph. If United "didn't take that move forward" and did indeed take too long, it will be a mistake they live to regret.

Pedro has a goal and assist already in the Premier League. He has averaged four key passes and 3.5 shots per game in his two matches so far, per WhoScored.com.

It is a very small sample size, but it seems to suggest Pedro is having no difficulty adapting his game to the Premier League. His record with Barcelona was excellent, particularly in terms of his scoring record when he played regularly.

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With United's attack crying out for additional goals, and more penetration from the support forwards behind Wayne Rooney, letting Pedro go to a rival was a huge mistake. At the time, United fans were able to hope that was because the club had other targets.

Now it just looks as if they botched a deal that could have been vital to the season ahead. Unless Van Gaal can find a way to get United's front line firing, Pedro will be United's No. 1 regret.