He had injury issues in 2017, so let's set that year aside. 2018 to 2020 his xFIP was 4.13, 4.33, 4.15. His 2021 xFIP 3.94, an improvement on the previous 3.
The Mets have long had an astrocious infield defence, regularly throwing JD Davis at 3B, old Cano at 2B, Dom Smith at 1B. And I am aware FI stands for fielding independent, but no stat is 100% accurate and I kind of doubt the formula works very well for that Mets infield.
We've seen other pitchers take it to another level later in their careers.
Whatever the reasons, looking at the numbers and the improvement after leaving the Mets, a Matz QO is a reasonable proposition.