I agree. My point is merely that Castillo's BTV stands out to me as low, as Iast I checked it was negative and that caught my eye. So I used Hamilton as an example to illustrate my point, by pointing to a) he has +13 BTV (modestly higher than Castillo) and b) the fact that I think the Sox would do that swap (not to imply Seattle would).
Pretty much: heres a player who has +13 who I think the Sox and Sox fans would be happy to swap for Castillo, showing that I think Castillos BTV should be up around 13 and if he can be had for an outgoing package that nets to less than 15, hes a good target (for any club).
I like Castillo, and people are worried about regression, but apples-to-apples youd also have to be worried about Burnes regression if you were to go that route as well.
Whatever contract Burnes lands, Im quite confident, that the next day his BTV will be negative. Because you dont beat the entire open market for a marquee FA and then have an immediate surplus asset. The market is more efficient than that and will force you to overpay to get the last remaining FA ace.
I would still offer Burnes 260 / 8, but if you cant land him, Castillo makes sense to me as a target (and I think Sox would have competition trying to land him from other clubs, and would have to submit an offer that tops whatever Castillos BTV is right now).