Absolutely true.
And if the Sox were not concerned, Sale certainly appeared to be. He spent his entire career as the poster boy for underpaid, and could have easily gotten a deal in the neighborhood of David Price's if healthy, but instead took one in the neighborhood of Patrick Corbin. He missed almost the entire second half of 2018, and his 2019 he had a career high in ERA (by a full run!!!), FIP and HR/9 and a career low in IP and ERA+. That he had 14 good IP in ST means nothing. (Was he even facing actual MLB hitters?) Since that contract kicked in, he has 0 IP. It always looked to me like he knew he should take a deal now rather than wait and see about the market. And it may have turned out to be the right move for him to take the deal when he did.
Maybe he wanted to stay in Boston? OK. But so did Eovaldi, and he still made sure he stayed for as much as possible...