This is lacking a ton of context. Goff's limitations are clear, and its apparent that Goff has played in a very QB friendly scheme his whole career.
For instance, lets look at their Average Intended Air Yards per pass. Goff is the 4th lowest in the league at 6.6 IAY. Stafford is one of the highest, at 9 IAY. For reference, Russell "Deep Passes Only" Wilson is at 8.6 IAY on the year. This matches the eye test - Stafford's numbers come on harder passes, and he remains as efficient (or more efficient, even) than Goff, who plays in a scheme that takes the pressure off the QB, closely related to Shanahan's (Jimmy G 6.2 IAY, Mullens 6.6 IAY).
It's clear to me than Stafford is going to be both able to run the current scheme they have as good as or better than Goff, while also adding the deep passing skillset he possesses that Goff simply doesn't.
Stafford also outclasses Goff in both EPA and QBR (which is heavily based on EPA), both stats better indicators of overall QB play than passer rating.
Diving into the most recent stats they have, here's a graph illustrating their place on an efficiency plot measuring EPA/play and Completion % over expected.
[tweet]https://twitter.com/KryzivenTake2/status/1349035236827537409[/tweet]
Stafford, on a failing team with a lame duck front office known purely for their ineptitude, still outclasses Goff.
Stafford is easily the better quarterback, and keep in mind, they're not paying all of this just for Stafford, they're also paying to get rid of Goff and his untenable cap burden. The real criticism is that they extended Goff to begin with.