I don't know anything really about how the front offices really work. No doubt they'll continue to refine things but it's really all about the players. If their opinions on the players haven't changed then its really all about the big board and who's available. Who can they not live without (trade up) or who can they live without (trade down).
As far as our perception of who got a steal or who was overdrafted: that's all shaped by the media leading up to the draft. I wonder what information the GMs would get that hints at certain players no longer figuring to be available where they want to get them. We know that GMs and scouts and such lie during this season for that very purpose.
It definitely is the season to spread false info. My guess is no one gets bulletproof info. If you listen to very connected guys like McShay, you can get a vibe of what it's like. McShay starts to pick up the league value of players by talking to his connections. They may not say "man, I hope Banks is there at 10 so I can draft him", but they will talk fondly of him and maybe say things like "high on our board" or "we think he can actually play LT at a high level". Whatever it is they'll say... you pick up the context clues, and these media people pick up on these things for a bunch of teams and get a pulse of the league in that way. I'm sure the dynamic is you give a little info, get a little info.
And for what it's worth, it doesn't even need to be a lie. Let's use Jeanty. Maybe Poles loves him, right? I bet everyone does. Poles can say, "I think this kid is really special." That's Poles giving info to a guy like McShay. So now... McShay knows a couple things. He knows a GM is high on Jeanty, but he also knows the Bears are paying attention to RB and Jeanty specifically. However, while it's not a lie, maybe Poles loves Jeanty, but would never pick him at 10. Or maybe there's a list of guys he's secretly hoping are there instead. It's not that he lied about Jeanty, but mislead the direction he actually wants to go. And now that he's given info, he can probably prompt a convo on the OT class to see what McShay is hearing around the league.
So of course, anyone can lie or prop up one guy. I'm sure it happens a lot. But someone like McShay, who may talk to a majority of NFL teams, can at least get a feel of the guys who a lot of teams are talking about in a good or bad way and then you can kind of go from there. Ultimately, it's still guessing how they value the player and if they're telling the truth to begin with.