Let's just take a look at things:
QPR, we scored 0 goals. We conceded 1 goal. The goal came from a free kick a long way out that was given harshly against Sandro in the middle of the pitch. Full backs staying back would not have helped.
Norwich - A fudging disaster, but we only scored 1 goal... We conceded 2, our CBs weren't exactly on form that day. A mix up in the box was one goal, a long range shot not being closed down was another.
Sunderland - 0-0, we scored 0 goals.
Spurs 3 - Swansea 1 - Swansea's goal came from a good strike in the centre of the pitch, our full backs weren't caught upfield. But we scored 3 goals.
Spurs 1 - Man United 3. We scored 1 goal.
So the game we won was the only game we scored more than 1 goal. Your plan to resolve this is to take away a key part of our attacking strategy and improve something that isn't actually hurting us at the moment?
Looking at our best 11, (which we don't actually have right now) you get:
Friedel (GK, obviously not going to get us many goals or create many chances.)
Walker, CB (obviously not going to get us many goals or create many chances), CB (obviously not going to get us many goals or create many chances) , BAE.
Lennon, Parker, Modric, Bale.
VDV
Ade.
Parker is not an attacking player, I know he might be used in the build up but to claim he is one of our major attacking threats would be laughable. (He's great defensively and got a nice assist recently though, so I'm not a Parker hater, just like I'm not a Friedel hater or a CB hater.)
I'm really struggling to make any sense at all out of what you said, we're left with Lennon and Bale as wingers (although Harry likes to fudge with that concept) and we have Modric, VDV and Ade as our central threats through the middle. With our full backs not going past the halfway line, not only are we using attacking full backs defensively (which is worse than using VDV as a defensive midfielder, Parker as an AM or Defoe as a target man), we are taking away our width... We're allowing the opposition to have a wide midfielder and a full back for Bale and Lennon, we're also allowing teams an even bigger numerical advantage in their half and to top it off, we're leaving one of the players that makes the most passes for us back out of the game.
Yes, we would be very solid defensively with 6 players back at all times.... We're playing 3 relegation threatened teams and Fulham at home... Why are we playing for a draw?
A DM allows full backs to go forward without leaving us totally fudged defensively, that's one of their key features.
So in your world, say we have the ball... We have Parker, Friedel and our 4 defenders in our half... We have Ade up top, we have Lennon on one side, Bale on the other and Modric is probably around the centre circle with the balll... What are his options?
Ade has 2 CBs on him, VDV has a DM on him, Bale and Lennon have a midfielder on each of them and a full back in front of them....
The ball has to go to one of the 6 players we have behind Modric... We just became insanely easy to defend against. Congratulations on your "football is a simple game" tactics, they were simple to defend against.
we just lack a goal scorer to turn our possesion into goals.
You have just oversimplified again.
That back 6 you want to leave back might have possession all game. 100% possession. Ade isn't going to go back there and score a goal from his own box.
Possession gets turned into chances which then get turned into goals.
The middle part of that is key, because the full backs you want to leave back are a vital part of our team's build up play and our team's build up play is the thing that creates these chances for this goal scorer we lack...
The only thing about lacking a goal scorer is Ade has a bunch of goals and a ton of assists. He isn't the most clinical obviously, but how many goals do you expect this goal scorer to get? 13 goals and 11 assists in the league is actually better than scoring a few more goals but getting barely any assists... Still though, let's look...
Van Persie Arsenal 27
Rooney Man Utd 26
Aguero Emirates Marketing Project 22
Ba Saudi Sportswashing Machine 16
Dempsey Fulham 16
Yakubu Blackburn 16
Adebayor Tottenham 13
What kind of upgrade are we looking at here? RVP, Aguero or Rooney?
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If football was as simple as you make it sound, Harry would be the new manager of Barca...