Dude, you are taking this way too personally, which is very strange since unless you created the site none of these comments are directed at you. You keep saying they provide a very “comprehensive” description of how they come up with their projections, but here is their blurb on this piece of it for major leaguers:
Well gosh damn, it’s now clear as mud how they came up with that negative valuation for Yoan Moncada...lol. Again, you keep acting like coming up with a projected surplus value is simple math exercise and the reality is it’s not because future performance is uncertain. The prior season does NOT automatically predict the future season. I have no idea what BTV is doing to come up with a negative valuation (since they don’t explain their methodology!), but my guess is they are simply anchoring off the prior year. Meanwhile, well known projections systems like Zips & Steamer both project 3.3 win seasons for Yoan next year since they are looking at a broader set of data points and not just 2020 results. With no further growth in performance or with any inflation in the cost per win in free agency (so $9M per win in all years), his surplus value would be ~$60M. I personally would estimate his future production to be higher than what those models project (in this case more like a 4 win player), which would place his surplus value closer to $90M.
Regardless, the point here is that some of BTV’s surplus value projections (more than just Yoan) are simply bad, which undermines the tool. By all means keep using it as a reference point, but if you posted any outputs that involved Moncada for example you would be laughed at. This has nothing to do with White Sox fans overvaluing Yoan, but everything to do with BTV’s poor forecast model undervaluing him due to a bad 2020 season.