First, you have to know what he'd have gotten and would have gotten through ARBs, and BTV does not have that ability.
Then, you need to project what he'd get as a FA for the 2 years added to his control years. Where do I "feed" that into BTV?
Walk me through the "simple math."
There are easily 15-20 teams that would give us real value in a trade for Bello and ask for no money. Would they give more if he had just 3 arb years left? Yes, some of the cheap teams would, although a handful might not want him for his last 1-2 arb year costs, too.
What would Bello have gotten in arb for 2026 after two $15M fangraph value seasons in a row? (Not $15M, as arbs are not high for the early arb seasons, but the numbers have been on the rise, lately.) How about next year and 2028? How is the math "simple" when we have no idea how well he'll do. I think your low opinion of Bello is influencing your projections.