Edm started the McDavid era with Talbot, then Smith, then Campbell. Talbot made sense to start with as he covered for King Henrik nicely the prior season. Prospect was Broissant had put in an E and A season as a pro with good numbers. But, Edm never gave themselves more options. Put all of their eggs in 1 basket.
2016 - in round 2 could have taken Hart, but opted for smaller forward, and oft injured Benson.
2017 - took smaller forward Yamamoto over Oettinger
2020 - Took Bouglat over Wallstedt, but really, he'd arrive too late for the McDrai 2nd contracts to be the main man.
They took several goalies from round 3 onwards, but that philosphy and hope of finding a Shesk, Lundqvist, etc. is a luxury only when you have a legit starter for several years, like what Lundqvist gave the Rangers, what Vasi has been giving TB. Edm didn't have that kind of locked in starter for several years. They needed to give themselves more options in the event their goalie did not pan out.
Add to that bad goalie coaching and team defense. And they are where they are now. Markstrom as a UFA passed on playing with McDrai in favour of Calgary.