I'm not sufficiently knowledgeable in this area to say which of you is correct.
However I have come to suspect that patent articles often omit one or two crucial details (in the description or the diagram). There could be advantages for the inventor in doing so.
There is also the incentive for the inventor to say 'existing methods are problematic', and then claim these problems are solved by his invention.
So your understanding, and your observations, might very easily qualify you to fill in with comments, clarifications and corrections.