Since I'm basicially a Dortmund fan and secondary a Man Utd fan I can tell you alot about Sahin. Therefor I'll sum up his problems and shortfalls.
About Sahin and his dynamic/agility/whatever you want to call it:
Yes, Sahins dynamic is pretty poor. He is already at this limit, since he recieved special training on Dortmund already due to this. Thats why the only position he can play on the really high level in modern football is the 8 as an deep lying playmaker. Similar to Pirlo.
But thats not much a problem with a proper system and also the position he plays is the most suitable for him. The bigger problem, and thats what I already noticed at the turkish team, is that he needs trust from his team and trainer. In Dortmund he had this. Everyone knew there how good he is and that he can do things no one else could in the team. Every time Dortmund had troubles building up pressure and/or creating chances the ball came to Sahin. In the turkish team he had Emre infront of him who had all the trust and everyone was sceptical about him (after the early hype he had). He didn't recieve alot of balls in his plays (when he even was on his main position - under Hiddink he played once as a left defender for example) and weren't gutsy enough to play his long and at times risky balls.
That completely shut down his biggest strength. He can completely read a game, anticipate movements (in offense as in defense) and find gaps in the opponents team and abuse it with his great passing and technique.
Without trust by his teammates about this ability, he isn't ballsy enough to use this strength. In Dortmund he slowly worked himself up on a octothorpe(=is this the right word?) system with Kehl behind him. This in combniation with his injury (He actually isn't injury prone. He had like 2 injuries in his entire career so far) made him fail completely this season at Madrid.
Now get to the point on how to use him as player on a strategical system.
As I said earlier, he is a deep lying playmaker. So he can play on the 8 with a 6behind/beside him, in a octothorpe system (outdated imo) or in a 3 player center with 2 vertical players infront of him (don't like this though, since this system lacks the link to the only scorer - though it might be valueable on a counter team I guess).
Since the 2nd and 3rd options aren't interesting for Man Utd I come straight to the first and how to play him with Man Utd.
Basicially it would come down to a similar system as current Dortmund is playing.
-------- Vidic - Ferdinand -----
Rafael---------------------Evra
-------------------------------
----Carrick/Fletcher-Sahin------
-------------------------------
Nani-------Rooney-------Young
-----------Welbeck------------
Aside from his rather poor dynamics Sahin is pretty good in defensive work. As I mentioned he got great anticipation, which balance his average physique and poor dynamic.
In offense he will build up our attackings, he can do fast switches at counters and he can greatly bring our wings in position with his passing. Also he can make the difference on very defensive teams due to his game reading.
His excact positioning and movement of course depends on the opponent. He often falls even behind the 6. At Dortmund he was at times the last men on the field. Klopp even said in public that he does that too often. Therefor it would be benefiting having either a strong left and right back (in offense) or a offensive strong centre back.
With strong left&right backs he could fall behind the centre backs to make it 3-6-1 / 3-4-3 (todays systems are fluid anyway) during attacking or he could switch with the offensive strong centre back places to avoid zonal and personal marking.
Another possiblity would be as a classic 8, but with less charge to the front, since he requires to have the field infront of him for his great passing to excel. Since he can do pretty decent long-range shots this is the area he will go the furthest. Since his poor dynamic I would rather seen him not do that too often, since this could mess up the system, since he might not be back in time.
Another possibility might be just switching to Evra position so Evra can go ahead supporting young and Carrick/Fletcher will be alone on the 6.
If the opposing team is in possession of the ball he should be on a line with Carrick/Fletcher. He will anticipate passes in between the gaps while Carrick/Fletcher will take up the more physical duties of defensive work.
The biggest problem in my opinion would be the following: When we would get him and make our system to his requirements to work it could get problematic when he wents missing. I prefer having 2 creative players to be honest. Since we play with classic wingers we kinda need a creative 8 & 10 in my opinion. Either on the 8 or 10 I would like to see a bulky player with some good technique (don't have to be outstanding, but good enough to bring some creativity). Keving-Prince Boateng would be my choice here.
I hope this helped a little.
To sum things up no a pro/con list.
Pro:
- cheap
- outstanding passing and technique
- great tactical understanding and game reading
- good standards & longe range shots
- giving us creativity in midfield
neutral:
- left fooded
- right food is decent, too. though he don't use it often
- could be the next Sneijder/Robben
Con:
- poor dynamics
- requires specific use of his qualities
- can be problematic, if he wents missing since this could mess up the team rhytmic
- don't know how he will do with constant rotation on a team
