It's hard to disagree with your time value of money argument as it pertains to player development / timing (thx for articulating it), but it really depends on what Chychrun would've returned during that year or so we were trying to trade him. If I remember right (not sure), Columbus would've traded for him, but when he was like, 'hey I'm not going to re-sign with CBJ' they were out. I don't remember any other deals being particularly close but maybe mis-remembering.
To continue with your example (which definitely does apply to the point you made), what if Chychrun's initial offers were 30K instead of 45k? I'm not saying they were, I'm just saying we don't know what they were.
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From my point of view, BA hit an absolute home run with the OEL trade, maybe the best trade of the last decade, I can't think of a more lopsided one in recent memory (Brassard / Zibanejad was about the same tier, that was back in 2016). Chychrun went for a little less than what I was hoping for (was hoping for a late top-10 draft pick, we got 12th), and imo we were honestly lucky to get even that -- Ottawa was 2 points out of a playoff spot at the deadline (tied with FLA with fewer GP), they didn't make a move for a backup goalie (Quick was very available) and then promptly shit the bed. Meanwhile, Florida got hot and then made the SCF, not saying Ottawa would've made the SCF but they could've and probably should've made playoffs that year.
Anyway unless we know the earlier offers for Chych, we can't really say. I suspect (but don't know for certain) the market might not have been there because the guy was getting injured all the time. Dorion got desperate and made a fair offer, Benning was desperate and made an absolutely stupid offer, to continue with finance analogies BA tried to time the market and imo mostly succeeded, he probably did better than he would've had he tried to dollar cost average. Especially with OEL (not sure Chychrun).
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More importantly, being a couple years 'behind' in the rebuild to me doesn't matter as much because it gives Guenther, Cooley, Simashev, But etc more time to develop. I do think we can probably use another top 6 center and top 4 D, but if Simashev hits, our D will be built around Serg, Simashev and a more developed / better verion of Lam, not to mention Marino and Durzi. And / or maybe Kesselring and / or Koly rounding out that bottom pair. That's not too bad. Especially if Sima ends up a true #1 which we won't know anyway for at least a few years, imo if Simashev becomes a Norris contender that's a cup contending D-corps. So waiting a few more years is in some sense necessary I think