I posted the other day, that if it was one game, one playoff-run, or one season, the only quarterbacks I would prefer to Matthew Stafford are Mahomes, Allen, Burrow and Jackson. That's it. His mental toughness and clutch play are elite in my opinion.
As far as 'adjectives' ... personally, I don't over-use the word Great because it under-values true-greatness which, I believe, is rare. I would call Stafford "top-tier" and "exceptional" ... plus "clutch" which I consider critical to an NFL QB.
As to your 'lucky' question ... Yes, a dropped interception is 'lucky' for the QB that threw the pass, just as an interception that is deflected and lands in a defender's hands is 'un-lucky' for the QB. However, I am not familiar with stats that measure dropped interceptions, or how accurate that stat may be. Furthermore, I don't know where Stafford stands with regard to such a stat.
In your post that I initially responded to, even you said ... 'I don't know how things ended up'