Michael Carrick and David de Gea before their Champions League tie with Galatasaray
With one of the deepest and most talented squads in the world, Manchester United have far more to lose than gain during the summer transfer window.
Sure, they occasionally make big deals, but United's first goal in the offseason is usually to maintain their perennially skilled group.
This is shown by the fact that they've sold just one first-team player—Dimitar Berbatov—in the last three seasons (h/t TransferMarkt).
Ultimately, United should be looking to keep the following five players in red for as long as possible.
All stats and info via ESPN FC.
Carrick with the ball vs. QPR.
Although he's not the glamorous name that many fans crave, the Englishman is quietly effective for the Reds—his threaded through-balls serving as the main source of United's attacks.
His aerial and defensive play are somewhat weak, but those flaws are outweighed by the passing prowess he provides for the Reds. Via WhoScored, his passes are completed at an impressive rate of 87.8 percent in EPL play.
In a generation where so many players look to make highlight-reel plays, Carrick understands his role as a traditional central midfielder, making him an invaluable asset to the club.
De Gea keeping a shot out vs. Chelsea.
After an unconvincing start to his United career, David de Gea finally looks like the world-class goalie Sir Alex Ferguson paid £17 million for (h/t The Guardian).
Even with his struggles dealing with crosses, de Gea has impressed enough with his shot-stopping ability that United should wholeheartedly commit to him for the future.
His true value to the club will remain to be seen, however, as a possible move for Ronaldo might require him to move to Madrid (via International Business Times).
Rafael celebrates his screamer versus QPR.
A product of United's youth system, Rafael da Silva has always been a talented player.
On the defensive side of the ball, that talent has only begun to show recently.
As a Brazilian-bred wing-back, his technical, crossing and shooting ability were qualities that were expected of him as a youngster. (Other prominent players with similar attributes are Dani Alves and Marcelo.)
His defensive play, however, was not always so strong, as he lacked the physical strength and overall composure to be a reliable first-team option at United.
That has all changed with his current revelation of a season.
Contrary to United's aging and underperforming defense, Rafael's individual level of play has skyrocketed.
The Brazilian has been able to display a combination of physicality and speed that the trio of Patrice Evra, Nemanja Vidic and Rio Ferdinand (all at least 31) are starting to lose, occasionally covering up their mistakes with these attributes.
And with three goals and assists in EPL play, it is obvious that Rafael has added strong defensive play to his repertoire without completely abandoning his offensive talents.
That should make the 22-year-old, who has yet to meet his full potential, part of United's plans for the future.
Jones and Mesut Ozil clash at the Bernabéu.
There's very little Phil Jones can't do, and that's why he's so important to United.
The uber-versatile defender/midfielder is a sort of Swiss Army Knife for United, boasting the ability to shoot, dribble, man-mark, head and tackle.
That versatility, which which truly allows Jones to be the best player (at times) on both ends of the pitch, has not been seen enough this season due to Jones' nagging injuries (h/t The Guardian)
Their struggles without him (e.g. in the second leg versus Real Madrid) should be telling of the need for a flexible player like Jones in the lineup.
Van Persie watches on during United's FA Cup tie with Chelsea.
United have scored an EPL-leading 68 goals this season, and much of that has to do with the stellar play of Robin van Persie.
With 19 goals and eight assists thus far, the Dutchman has most definitely been United's finest offensive player, leading what has been an extremely potent attack.
Simply put, you can't win unless you can score, and van Persie is United's No. 1 option to do just that.
He's not going anywhere.