Anyway, TotalZone is roughly analogous to Dan Fox’s SFR in methdology and value. It’s a huge step up from FRAA, imo, and is in the second tier of stats with other psuedo play by play metrics. Basically (and I’m 90% sure what I’m about to write is accurate) it looks at retrosheet data to map out who fielded the ball and get a rough idea of what kind of numbers are average at each position. It’s not a true play by play metric that includes actual BIS or STATs zone data but it’s a healthy approximation. I’d have confidence that as long as it doesn’t wildly diverge from the scouting report, you can probably find a +- 5 range for their defense.

The usual caveats to defensive statistics still apply.