You know full well the game is much faster than it was when Pirlo was younger, and when he was older he had 3 other midfielders to run for him...is that what you're advocating?
There's a reason Weigl has always played in a 2, which means we'd need to drop Silva or De Bruyne to accommodate that player to hold his hand defensively.
The reason Weigl has always played in a 2, which he hasn't ALWAYS but let's just carry on, is that Dortmund have always generally played in a 2 or 3. This is like saying that Yaya has always played in a 2 or 3 so he's incapable of playing alone apart from all of those times he played successfully alone.
And Weigl's lack of athleticism is overrated. It's the typical adherence to physicality which out of every club on planet Earth, City fans should see is nonsense.
And he doesn't need anyone to "hold his hand" defensively. He's a better defender than every person currently employed by City including the centre backs.
We're looking at different things. You're looking at his body. I'm looking at his brain. I'm pretty sure he'll end up as a City or Barcelona player and in several years everybody would always have said that he was going to be great.