It happens fairly often. A 33-win team is bad; a 49-win team is good. That's +16. Rare, but certainly not unheard of.
The value of young talent depends on that talent's ceiling. The Wolves have young talent that can reasonably be expected to get much better. It's not clear with the Sixers, because they are so heavily invested in young bigs who are injured. The Suns' youth core begins with Bledsoe and Knight. Bledsoe is improved over last year, so that's good, but I suspect that Knight is what he is. And what he is isn't all that good, so that negates his "youth" advantage. Part of the reason he shoots so many 20-footers is that the defense is usually able to take away the rest of his arsenal, and that's a result of his poor handle and lack of size.
Len, Warren, and Booker all look like they have room for improvement. Probably none will ever be an All-Star, although you never know; but it's not too optimistic to project them as solid starters.
Calling Teletovic or Leuer part of the future is silly. Players of that caliber almost never stay in one place for long. You find the occasional exception, like Nick Collison in Oklahoma City, but you're almost always looking at a two- or three-year relationship with that level of player, at the most. Just pick a few players of that caliber around the league at random, and see how long they've stuck with their various teams.
Overall I'd say that McDonough has done a slightly better than average job. Warren and Booker appear to be above value for their draft positions. The jury is still out on Len. The Suns mishandled the three-PG situation last year, and it cost them some PR and the future Laker pick. Bledsoe will bail them out of that mess if he continues to improve. Investing long-term in the Morris twins was a mistake, but at least their contracts were modest, and one of them has already been shipped off -- good damage control there. The Chandler signing was excellent and the lower-level FAs have been hit and miss, which is what you'd expect.
Similarly, the Suns' intermediate-term future is probably average or maybe slightly above. They don't have anyone who is a top-20 player in the league, and it's tough to get good until you have at least one of those. Maybe Bledsoe will get there, or maybe it will be Booker in a few years. (SG is a weak position league-wide, so there's an opening there.)