One of those first's had to do with convincing Detroit to take on Goff's huge pay liability.
I said in a post several days ago that not only would the Rams be lucky to get a bag of potato chips for Goff, but very likely the Rams would have to include draft picks in any deal they made because Goff's contract was so onerous. That is, they might get a marginal starter for Goff plus a 2nd rounder or more. Turns out the cost for dumping Goff was even higher than I thought.
But in the end, the Rams got a good veteran player who is highly regarded in this league. And even just good QBs are very hard to come by in this league and only rarely change teams via trade.
Stafford wanted out of Detroit. The Rams wanted rid of Goff. Detroit needs to rebuild. The Rams think (right or not) that they are ready to be elite. Detroit has the cap space. It is one of the few practical (not fantasy football imaginations) ways for the Rams to upgrade at QB and move Goff and be able to make it happen in a reduced cap year.