We have discussed this on other threads, mostly regarding Jake Gardiner, but I found this article at espn insider and wanted to share... Mostly because it supports my argument, of course.
Its an 'insider' article, so I copied and pasted the relevent bits....
The reclamation project
Since 1990, about 11 percent of first-round draft picks have been traded before playing a single NHL game. (We'll call them "traded players.") Most of these prospects were not traded in blockbuster deals; they were, to some extent, reclamation projects.
For traded players, the failure rate is alarmingly high. Only about 54 percent of them turn into NHL contributors (min. 82 games played). Compare that to all other first-rounders, who become contributors 74 percent of the time.
But even if traded players beat those odds, they struggle when they reach the NHL (see chart below):
Trading Damaged Goods
First-rounders who were traded before their NHL debut do far worse than those who aren't traded.
|First-round picks||Pct. To 82 NHL GP||Overperform draft slot (Min. 82 GP)|
|Traded before NHL debut||54%||0.47 GVT/season|
|Not traded before NHL debut||74%||1.45 GVT/season|
In addition, first-rounders who are traded reach the NHL at a much slower pace. They make their NHL debut in about 2.5 seasons; the average first-rounder debuts in about 1.5 seasons.
Basically, if a first-round pick is traded, it usually means some GM doesn't think he'll play up to expectations. It could be injury concerns or a developmental delay. Or the team might be admitting that they made a scouting error. Either way, there should be red flags raised every time a former first-rounder is dealt before reaching the league.
So, usually, trading for another team's former first rounder doesn't bode well. But it could be a low-risk opportunity to add some value and, if nothing else, a chance to give a kid a second chance.