That ignores the impact of injuries over the last several years, unless you are blaming Thompson for them. And I hope we won't find out but I'll bet the team responds much, much better to the absence of Rodgers this season. Having both Flynn and Tolzien in the off season program will make a significant difference.
I find the injury issue to be a matter of assumption and not demonstration.
Besides Rodgers, and other than Bishop, Collins and Bulaga over a few years, I'm not seeing where the impact is meaningful nor am I seeing the situation to be meaningfully above the league average. Most teams lose starters for some games (like Matthews) either through injury or suspension and the league is riddled with quality players having IR seasons and career ending injuries each year.
Many IR seasons occur in the offseason, camp or preseason that don't get counted in the "lost starter games" stats. Guys with career ending injuries come, go, are forgotten by that team's uninitiated, and are also not counted in the "starter games lost" all across the league.
IR seasons and career-ending injuries to mediocre starters and backups should be pluggable if the GM is one of the best in the league, tapping into some value in the free agent market if necessary.
This does not even consider the Packers' conservative approach to injuries, one that might inflate games (or even careers) lost. David Wilson is a recent example ripped from the headlines. After sustaining a neck injury it was discovered he had spinal stenosis. He was recently cleared for practice regardless. Then he took a hit to the head and sustained numbness in his extematies. Only then was he counseled to retire, which he did. If Collins or Finley or Jolly were Giant draftees they might still be on the field.
By the way, to whatever extent Flynn or Tolzien might be judged above the league average at some future date correlated with a commensurate record above 0.500 record in relief, then this would simply reinforce the notion that the roster outside the QB position is not particularly strong.