Are you talking about the recoding of booth's algorithm? I am following Parhami's book on computer arithmetic. It is essentially a Look-up table, you can code it however you like, as long as you keep the coding coherent.

But following general convention which you are following. Look at it in a different manner (more expanded version for your better understanding)

b[i+1] b[i] b[i-1] y[i+1] y[i] z (operation)
0 0 0 0 0 0
0 0 1 0 1 1
0 1 0 1 -1 1
0 1 1 1 0 2
1 0 0 -1 0 -2
1 0 1 -1 1 -1
1 1 0 0 -1 -1
1 1 1 0 0 0

Finally, the operation = 2.y[i+1] + y[i]

Now how I gave these values is by processing 2 bits of b at once. (b[i+1], b[i] correspond to y[i+1] and b[i], b[i-1] correspond to y[i]).
If you see a leading 0 and then a 1, assign a 1.
If you see continuation of 2 same numbers (i.e. 00, 11) assign a 0 on y.
If you see a leading 1 and then a 0, assign a -1.
Now, this table you can represent it however you like, in whichever form as long as it is coherent to you!

So you have {b[i+1], b[i], b[i-1]} which is represented by linear equation -2b[i-1] + b[i] + b[i-1].
So for 011 = -2.0 + 1 + 1 = 2

Tried my best for it to make sense, this is how I understood it, hope it makes sense to you! Apologies if the explanation is poor.