Ultimately that team just wasn't good enough, and a big reason for that was between the pipes. Grubauer was stellar the first two games and then promptly imploded. The goal he gave up against Nick Holden is right up there with Rahim Moore and Joel Quenneville in sports decisions/moments I will never, ever, EVER forgive.
But you absolutely CANNOT just throw the coaches under the bus here, management simply did not go all in. They half-assed it like they did every other deadline (except 2022 of course) when they acquired the washed-up remnants of Carl Soderberg and Patrik Nemeth. In addition to that, this was right around the time Ryan Graves inexplicably got super-panicky every time the puck landed on his stick. The depth wasn't there, the talent wasn't there, the goaltending wasn't there, and the defense was most definitely NOT there.
Maybe Sakic realized the team just wasn't "ready" yet and did not invest fully until the following season. Regardless, they could've had the love child of Toe Blake and Punch Imlach behind the bench and it wouldn't have made any difference.