You need the have good players around you. His offensive line was makeshift learning to work together because of injury. 2 of the big 3 WRs were out.
Only a handful of QBs can do it without that strong supporting cast. Look at Brady looking so normal this year with the drop off of weapons. An Aging Aaron Rodgers, the greatest player in NFL history, just looks like another guy with that horrific supporting cast around him.
Back when the Rams were rolling on the greatest show, it didn't matter if it were Warner, Green, or Bulger, you have the playmakers and a decent line and a good QB will be successful.
Some will point to the schedule, but the reality is Cooks, Woods and a few weeks of the new offensive line gave Goff a chance again and he proved he can be a good QB in the league as he has the last 3 seasons.
