But a suggested transfer alternative is Espanyol's Hector Moreno. Here is a scouting report on the 6'0", 176-pound 26-year-old Mexican international.
Issues With Hummels
You should not continue to overlook Hummels' shortcomings.
Just because he is a marquee name with an extravagant playing style does not mean he should be exempt from constructive criticism.
His long pass completion percentage is 64.6, so this notion of him being anywhere near the class of two-time Ballon d'Or winner Franz Beckenbauer is fallacious.
For every successful deep pin-point pass, there are several inexplicable wayward passes where you think to yourself: "What was Hummels' thought-process for that pass?"
This is why Hummels' pass completion percentage is up and down.
Defensively, he is strong in standing tackles.
Yet, unfathomably he still has a penchant for high-risk challenges.
His tendency for impetuous tackles, like fouling Borussia Monchengladbach central midfielder Havard Nordtveit from behind, is not just a red-card offence but raises a red flag regarding his football IQ.
One word to describe Hummels is mercurial.
Real Madrid left forward Cristiano Ronaldo, Italy's Antonio Cassano, the Swiss national team and a host of unheralded Bundesliga players have taken advantage of Hummels' defensive lapses.
His teammate Ilkay Gundogan spoke out against the criticism of Hummels last September.
"Every player goes through difficult periods like these," Gundogan said, per Ruhr Nachrichten (h/t FOX Sports). "I am not the least worried about him. Mats is still one of the best centre-backs in the world in my opinion."
With Louis van Gaal expected to take over the reigns at United, per Mark Ogden at the Telegraph, there could be a personality clash between the UEFA Champions League-winning Dutch manager and Hummels.
"Van Gaal was a pompous *expletive deleted*. He wanted to be a dictator, without a hint of gleam in his eye," Paris Saint-Germain centre-forward Zlatan Ibrahimovic said, per his autobiography I Am Zlatan Ibrahimovic. "There was a lot of five goes here and six goes there, and I was glad when I could avoid him."
How is Hummels going to react when he is being screamed at in front of his teammates by Van Gaal?
Hummels feels a sense of entitlement, and it factored into his brazen claim that German national team manager Joachim Low was anti-Dortmund, per ITV.
Van Gaal is a different beast to Low and will castigate anyone, per Raphael Honigstein at Sports Illustrated:
Van Gaal's authoritarian style [at Bayern] rubbed plenty of people the wrong way to begin with.
Success on the pitch made them put up with him, even when he employed some unorthodox methods—he once showed them his genitals—to motivate them.
Publicly, the players insisted Van Gaal was treating them fairly but they felt increasingly exasperated as this car crash of a season progressed.
After one particular bad dressing-down, Holger Badstuber was close to tears. Even Arjen Robben distanced himself from his compatriot.
"His management style reminds me of that of Felix Magath," said [Bayern chairman Karl-Heinz] Rummenigge. "It doesn't win you any friends."
There should be question marks over Hummels' suitability to being a big-money acquisition at United.
One transfer alternative is Espanyol's Moreno, a former Van Gaal player at AZ.
Moreno reads and reacts quickly in adverse situations.
This was evident with a last-man tackle to rush then-Valencia (now Newell's Old Boys loanee) central attacking midfielder Ever Banega into an ill-advised shot as he had a three vs. two situation in Valencia's advantage.
Moreno demonstrated excellent recovery pace when he made a goal-line clearance to stop then-Levante (now Seattle Sounders) centre-forward Obafemi Martins from scoring.
Villareal centre-forward Jeremy Perbet was another victim of Moreno's positional awareness, who darted for the line and cleared the goal-bound shot.
Moreno generally is in the right place at the right time as Real Madrid centre-forward Alvaro Morata found out when his header was headed clear by Moreno.
He is a seasoned footballer who brings experience: He has seven seasons of European football under his belt, was a member of Mexico's acclaimed youth international teams, played at the 2010 FIFA World Cup and has accrued 50 international caps.
Moreno has flashed potential as a prolific ball-winner, like winning back the ball 11 times against Malaga (six interceptions, five tackles), per Squawka.com.
However, Moreno's ball-winning productivity is not prolific.
|Tackles Per Game||La Liga Ranking|
|Tackles Per Game||1.5||147th|
|Interceptions Per Game||1.7||94th|
His interceptions per game output has diminished by 50 percent when compared to his 2009-10 season (3.4).
Why is this the case?
It has to do with Moreno's playing style which is retaining the dominant defensive position, jockeying and forcing the opposing player into a mistake.
The drawback is Moreno has to be flawless and error-free, which has not been the case.
He inadvertently headed the ball into the path of then-Mallorca (now Villarreal) centre-forward Giovani dos Santos, who went on to score.
Moreno recklessly brought down Atletico Madrid centre-forward Diego Costa to concede a penalty.
Moreno can be emotionally fragile which hinders his performances.
Like Hummels, Moreno overcomplicates passes and needs to up his pass completion percentage (78.6) into the high 80s.
In 2004, Roma's Walter Samuel was the big-name defensive transfer target for Europe's major clubs.
He had been linked with United two years earlier, per Adam Marshall at Sky Sports.
United did not sign Samuel, so Roma sold him to Real Madrid in a £15 million deal.
Whatever hesitations United management had in Samuel were realised—he lasted one season at the Santiago Bernabeu.
Meanwhile, then-United manager Sir Alex Ferguson opted for Gabriel Heinze, who was signed from Paris Saint-Germain for £6.9 million.
There are warning signs in Hummels which United management should investigate before spending big on him.
If United are looking for a cheaper alternative, Moreno is a viable option.
Statistics via WhoScored.com