Just perusing through the draft, a couple of top 3 picks who took that long:
- Dylan Strome (2015): played 7 games in 17-18 and 21 games in 18-19, but has turned into a solid player (although not for the team that drafted him).
- James Van Riemsdyk (2007): Stepped into the NHL two seasons after his draft and was immediately a solid player
- Jack Johnson (2005): Played 5 games in 06-07, but didn't play a full season until 07-08
- Bobby Ryan, 2nd overall (2005): Actually didn't make an impact until 08-09, which is super long for a #2 OA
The list is not extensive, and I have a feeling the 2005 guys are a little bit delayed because the lockout meant that teams were debuting guys from TWO drafts in the same year.
So you are definitely correct that teams rarely have to wait that long for a #3 pick, but how often do the teams picking in the top 3 immediately needed their player to contribute? The Coyotes finished many points out of the playoffs in 16 and 17. The Flyers definitely could have used a player to help immediately - they made the playoffs both years after JVR was drafted, including the conference finals in 07-08. Had they taken Sam Gagner (6th OA), perhaps they might have fared better - he came into the Oilers lineup immediately and was pretty solid.
Jack Johnson and Bobby Ryan are interesting in that their teams won the next two Cups, so it's hard to argue taking someone else would have made much of a difference. It wouldn't have mattered for the Ducks - there was no player other than Crosby from the 05 draft who made an immediate impact, so it wasn't like they could have taken someone else who would have helped win the conference final in 06. And they won in 2007 anyway.
Had the Hurricanes taken Anze Kopitar, though, perhaps they wouldn't have been a one-hit wonder. They won the Cup in 06 and then proceeded to make the playoffs once in the next twelve seasons, despite having decent teams most years (i.e. they were missing the playoffs by only a handful of points most years).
I guess the question for this year's Ducks - does it matter if their draft pick contributes sooner rather than later? I think they're hoping to take a big step forward this year, but I don't think making the playoffs is realistic, with or without their draftee in the lineup. But it might make a difference the season after.
Sorry, that's a lot of words to say that it's a legitimate question. Is Silayev's value to the Ducks driven down by the fact that he can't play for them for two years?