We describe a new capability of the Wang-Sheeley-Arge (WSA) model to routinely derive the coronal separatrix web (S-web) as a standard data product. We use one Carrington rotation (CR) to demonstrate this tool, in which we derive the global coronal magnetic field and S-web using a sequence of synchronic photospheric field maps from the Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model. We also derive a time series that quantitatively relates the in situ observed solar wind at ACE with the squashing factor ($Q$) derived at the model-determined source region of the solar wind, where high $Q$ indicates the source region proximity to a magnetic separatrix or quasi-separatrix layer (QSL) in the corona. We demonstrate that all intervals of high $Q$, including one associated with a pseudostreamer, correlate with times when the charge state and abundance measurements at L1 are enhanced and highly structured. This is predicted to occur for solar wind originating from the open-closed boundary, where closed field plasma with escapes out into the solar wind via interchange reconnection with open fields. Further, we relate $Q$ to expansion factor ($f_s$) and coronal hole boundary distance ($\theta_b$, DCHB), which are longstanding parameters used to empirically derive solar wind speed. We demonstrate that $Q$, though related to $f_s$ and DCHB, is a separate metric of the coronal magnetic field topology and a unique probe of solar wind formation. We conclude by highlighting the novel capabilities of this tool, and we discuss future uses for space weather forecasting.