Fool's gold, pure and simple. Vlad so far is a one season wonder--2021, age 21, when he hit 48 dingers and had an OPS of 1.002.
In his other 5 seasons, his OPS's have been .772, .791, .818, .788, and now .815, and his dingers have totaled 15, 9, 32, 26, and now 14.
In 2013 the Yankees signed Jacoby Ellsbury for 7 years and $153M, largely on the basis of one freaking season, 2011, when he had 32 dingers and an OPS of .928. He never had another season remotely as good before or after 2011.
I think Vlad's a lot better than Jacoby turned out to be, but I think he and his agent are expecting a long term contract based entirely on his 2021 season (48 dingers, 1.002 OPS). In addition, because I think Vlad could be a fan favorite in Toronto, I'm assuming he and his agent will use that fact to demand a big contract, which officially doesn't have to be offered until after the 2025 season, but will definitely come into play if Vlad is headed for the Sox.
Then there's the little matter of Vlad's weight, which is currently 245 lbs. Anyone here remember Sandoval? Anyone? The Sox swept in and took him away from the Giants and paid him $17M/year for doing basically nothing.