Here are two crucial points in how his alternatives were chosen:
1. The player must have played on the left wing for an extended period this season.
2. The player needs to possess the upside to reach Reus' level.
Feel free to comment below with your own Reus alternatives.
In 18 months time, Kostic's name will be filling up the transfer gossip columns.
Receiving the ball from left-back Giliano Wijnaldum, the younger brother of Dutch international Georginio, seeing Kostic gallop down the left flank and find a way past the opposing right-back has become a common sight.
Statistically, Kostic won't wow you, four goals and four assists in 14 league games this season, but he is full of energy with and without the ball.
He averages more tackles per league game (2.4) than Phil Jones, Tom Cleverley (2.1) and Michael Carrick (1.9), so Kostic's work rate puts him in the good books of Manchester United manager David Moyes.
Groningen are anticipating to be paid in full by major European clubs, such as Manchester United, for Kostic, 21, not on his limited body of work but because of the p word—potential.
Twente's front three: Quincy Promes, Luc Castaignos and Dusan Tadic have combined for 20 goals and 14 assists this season.
Then you have the vulture in Shadrach Eghan pouncing on loose balls.
The midfield is powered by the industrious Felipe Gutierrez and his sidekick Kyle Ebecilio, the former Arsenal player, who is getting his career back on track.
Twente are a well-drilled attacking team, and you shouldn't be surprised to find out they lead the Eredivisie in goals scored (33 in 14 games).
Gutierrez may control the game, but it is Tadic who creates goal-scoring opportunities for the team.
Only one player in the Eredivisie averages 4.0 key passes or more per game—Tadic (4.4).
What is a key pass? A pass that leads to a teammate shooting.
In the past, Antoine Griezmann has proven he is technically a very good dribbler, but he only averages 0.7 dribbles per game this season.
It is clear he is emulating Cristiano Ronaldo's pragmatism; cutting down the dribbling, passing, moving into space, shouting for the ball and shooting as opposed to flashy step-overs and toying with defenders.
The first option produces more goals than the second option.
This process is working for Griezmann in La Liga this season; eight goals in 12 games.
However, he's been misfiring in the UEFA Champions League, no goals thus far.
Koke has sublime ball control, high football IQ, excellent positional discipline and will sacrifice for the betterment of the team.
He is the opposite of teammate Raul Garcia who is a gunner and will shoot on sight.
Koke has found himself in the opposing penalty box plenty of times but generally passes the ball.
This is why his key passes (34) are almost double the amount of his shots taken (18).
Now this is fine if Diego Costa, David Villa or Garcia score, but if they don't, then it is a missed opportunity for Koke.
He needs to be a dual-threat.
Five of his eight assists have come from the left wing, but he spends most of the time cutting into the middle and dictating play.
He has the characteristics to be a world-class No. 10.
Timo Werner is not as pacey as Ibrahima Traore, one of the fastest players in the Bundesliga, but since Werner is more bulky, has better ball control and is German, Traore will need to find a new club.
The left wing now belongs to Werner, and even if he goes through a rough patch, expect Stuttgart rookie manager Thomas Schneider, who coached Werner at U-17 level, to give the teenager the benefit of the doubt.
According to German football expert Clark Whitney, Werner will end up being a No. 9.
Werner's finishing when he has dribbled his way through on goals has been precise, three goals from 13 shots.
Vedad Ibisevic, Stuttgart's leading scorer in the league, will be nudging Schneider and saying, "Keep playing the kid on the wings."
With Adnan Januzaj showing so much promise, do Manchester United need to sign someone on the left wing?
This is why signing Marco Reus might be beneficial to your FIFA 14 ultimate team, but in real life, it will stagnate Januzaj's progress.
Januzaj is to Manchester United what Werner is to Stuttgart.