Realistically, and the original video admitted as much, Drew Lock probably isn't a 1st ballot HOF QB even if he does become a perennial starter. I think the point is that you can see significant improvement with a change in environment. Denver sincerely hopes their new QB improves aspects of his game in his new city.
2 things
1)It's hard to draft a franchise QB. ...and there are easily identified examples of QBs changing teams and becoming good to really good. It's beneficial to try both avenues because the odds are stacked against each individually. Matt Flynn didn't win the job 10 years ago, but maybe this time ....
2)I'm thoroughly convinced that the situation changes the outcome as much as the talent level. DK's better because he was drafted late and it motivated him. RW3 as well. Sherman always showed the extra effort because he felt slighted. Jamarcus Russel (and fill in your favorite bust) didn't fail because of talent. It was motivation (and maybe some environment). If Drew Lock goes through the same process in '22 as Drew Brees in '06, he could easily be Tannehill or Cousins or Bridgewater or Bledsoe and maybe a lot better- Brees, Alex Smith, Kurt Warner (cut from Green Bay before Arena League). He could also be Sam Darnold. That (I think) depends more on Jan-Sept '22 than 2019-2021.
I hope Drew Lock reads .net I hope the posts that doubt him are motivational and I hope the posts that hold high hopes also motivate him. Sure there's doubt. I bet he doubts himself at times. But to quote someone that absolutely knows it to be true, "Why not us? Why not you?" Why not Drew Lock?