I guess the way I think about it is this.
Imagine you are a young kid who just came out of school / college / university, and you are looking for a career job for the first time in whatever career area you want to work in - lets use IT/Computing as an example, because that's the industry I work in.
So imagine you finish your study, and you get your first job as an intern at a big company that has a good team of guys, great management and good structure. As you come in they spend the first few weeks just giving you formal training, because they already have a strong team so they don't have to force you in to the job - they can afford to take the time to train you properly.
Imagine your team leader is a guy who has 10 years of experience in the field, and started off in the same entry level job you started in now, so he knows all about how it was when he started out, and what he did to get to where he is now. He's happy to share all of that knowledge with you to help you develop your skiils (both job skills as well as teaching you the right mentality and life skills). He pretty much takes you under his wing and tells you that if you ever have questions about anything, you can come to him any time.
When it comes to formal training, the company believes in their young staff as the future of their organisation, so they will pay whatever that have to in order to get your all of the training and certifications you need to make you in to the employee they need.
After two or three years with the company you know all of the tricks of the trade, you have all the certifications you need, you have learned how to act in a professional/corporate environment, etc.
Now think of another scenario.
Same kid just finished study, gets a job with a small company that's not been around very long. It's a small team of 3 guys plus the manager. Because of lack of staff, as soon as you start with the company they expect you to get to work right away. They don't give you more than a day training, then they throw you in the deep end and expect you to learn on the fly. The manager has to manage the entire business operations as well as your little team, so he is way too busy and has his hands full - has no time to train you, to mentor you, to sit down with you and spend time with you. Because of this, the guys in your team (who are in the same role you are in) end up your mentors.
These guys in your team certainly have more experience than you (as you have none) but they still don't have a lot. None of them have been working in the industry for more than maybe 2 or 3 years. They send you on site to fix issues you have never dealt with before, and when you call them for help they are too busy, so they just say "you'll just have to figure it out".
It's a small company so they cannot afford to train or certify you - you need to pay for this out of your own pocket and do your study in your own time after hours. That leaves you pulling late night study sessions and coming in to work tired.
The way I see it there are two types of people. The first type is the person who is self motivated, high on confidence, hard working. In the second scenario that person will take up the challenge - he'll do his own research, he'll find solutions for problems, he'll do his own extra study, and he'll get by just fine. He might even do better in scenario #2 because by doing all of this himself he has the potential to learn more and to grow to become self-sufficient and a leader, skills that might help him a lot in his next venture. In the first job he will still do well, but he might be held back somewhat by being in a very pidgeonholed role where he is limited what he can do, and has to spend so much time being spoonfed all of his training when he just wants to get out there and work.
The second type of person is the one who is maybe a bit immature or a bit low on confidence. This person in scenario #1 should excel because they get to ease in to the situation - they get all the training they need, they get that nice mentor to help them through uncertain times, and they don't need to rush in to the deep end until they are ready. Once they are ready their new found set of skills and abilties might give them a big boost in confidence, and then in a year or so they are just as good as anybody out there. In the second scenario they probably wont fare so well. They'll get thrown in to the deep end right away, and they will probably make a mistake at some point. Then they might get really down on themselves, fear going back out there and making another mistake. Try to train themselves but don't know where to start, and due to a lack of guidance that training just never happens. They don't know how to carry themselves in a corporate evironment so they just get confused and overwhelmed. In the end it all becomes too much for them and they just implode mentally...never end up developing the skills or confidence they need to be the type of employee they could be.
I think basketball is much the same deal because what you need to remember is that we think of basketball as sport and entertainment...for these guys it's a job. It's what brings home the money, puts food on the table, puts a roof over their heads.
Every year there are a ton of young guys in the draft. Some are so called 'NBA ready' players from the start. They have NBA ready bodies, they have great maturity, they have high levels of natural talent and endless potential. These are usually the type of guys who can (and probably will) excel no matter what team they end up on. Guys like KG, Tim Duncan, Michael Jordan, etc.
Then you have the guys who might have great natural talent, but they aren't so mature. Maybe they have confidence issues, or they are still quite raw and need to develop alot, or maybe they have maturity issues or personality issues - selfishness, arrogance, etc. If guys like this end up going to a bad organisation, then I think more often than not it holds their careers back dramatically. Guys like Andre Blatche, Jordan Crawford, Josh Smith, Demarcus Cousins, etc. All the guys on their team are young like they are and their coaching staff and management are questionable, so they never really have that guy who can take them under the wing and mentor them...show them the ropes. Show them the right way to act, the right attitude to have, etc. Usually these teams are bad teams also, so they need to come in and play big minutes right away - thrown in the deep end so to speak. They pick up bad habits (i.e. becoming selfish chuckers) and there is no great mentor there to guide them away from that and teach them the importance of team play, etc...so these bad habits stick. After 3 or 4 years in that team their reputation is already soiled - everybody knows about their bad habits and bad attitudes. Nobody wants them. Their confidence goes low. They get used to losing, they get frustrated. Their careers basically implode under them.
Look at the transition Jordan Crawford made going from Washington to Boston. He still showed signs of those 'bad habits' but he played the best basketball of his career as a Celtic. Got traded away, now he's back to his old self again. Dame deal with Blatche in Brooklyn.
How much better has Demarcus Cousins with better management around him?
Imagine how good those three guys could have been if they went to a team like Boston, San Antonio or Chicago on draft night?
I think Rondo is one of those guys too. He had a lot of weaknesses in his game when he came out as a rookie. Had the arrogance, the selfishness, the 'immaturity' you could say. He came to Boston and apparently none of the big 3 got along with him that well, until he started to change his attitude somewhat to earn their respect. Those guys largely became his mentors, and he grew into one of he best PG's in the league. If Rondo started off being drafted to Washington or Sacramento...what kinda of player would he be today? I think he'd be half the player he is now. I think his own arrogance would have eaten him alive, and he'd be one of those guys no GM would touch.
So in short yes, I think the team that young guys get drafted to makes a huge difference to the vast majority of young guys out there. I think theres really only a handful of guys in each draft who can end up on a crappy team with crappy management, and still become a great player.