I watched Jack Johnson in college a lot. I live in Michigan, we get (then) CCHA games on FoxSports Detroit. I just think he thinks offense first, and only offense sometimes. And Berenson never reined him in, he just let him run wild. I think it's very fair to criticize Berenson for it. He got away with it still in the NCAA. But he never had to fight his way through the AHL.
A good example of that type of dman who has a ton of skill, skating etc and was dumbed down into an average two way defenseman....instead of a stud offensively who played hard in his own zone and gradually got better at that part of the game would be....
Brad Stuart. He came into the league expected to be a #1 offensive d-man, and instead he's turned himself into a hard-hitting, dependable defenseman who can chip in some on offense. But it was rough getting there for him.
I'll give you the anti-Jack Johnson: Jonathan Ericsson. Not many people realize that the season before he was drafted, he was playing as a center in Sweden. According to Wikipedia (I looked up to get details right) he was playing center as recently as 2001-02 for his junior team there. Hakan Andersson allegedly caught him at an odd game where he was forced into temporary defensive duty due to roster issues, and after seeing him play he talked the team into keeping him there, then the Wings drafted him in June 2002 as a defenseman, the very last pick of the draft.
He then spent from 02-03 to 05-06 in Sweden learning at D. In 06-07 he was brought over to the AHL and in I think 07-08 was an AHL All-Star. He had small stints with DET between 07-09 and DET fans were really excited about him. And then 09-10 happened and he STUNK. And he spent the next couple years being considered by many as a wasted expirement. I've even personally really disliked him and wished he'd been gone many a time. DET even skated him at 4th line forward once or twice due to injuries.
Sometime last year though, in the shortened season, things finally began to come together for him. At the moment he's a legit 2nd pairing d-man in the NHL IMHO. He unfortunately is having to play top pairing duty with Nik Kronwall and that's probably asking a bit too much of him.
The point of this is though that a big center can be converted into an effective NHL defense-first defenseman fairly late in his development. And yet a guy like JJ, who'd always been a defenseman, just can't corral in his own offensive desires and mindset... and to be honest never had anyone slap him around a bit and tell him he needed to. And not it's probably too late. For all the offensive glory people remember Paul Coffey for, Coffey was HORRENDOUS in his own zone, embarrassingly so. Coffey'd get eaten alive in today's game. Orr probably would too, if we're being honest.
One of the reasons Danny DeKeyser was so attractive to the Red Wings is that he skates well and he plays well first in his own zone. They want that good first pass from him and anything else is bonus. One of the reasons Brendan Smith is such a disaster in DET is his offensive decisions are poor, and often at the expense of his defensive responsibilities. He's still kinda' a hot dog, and everyone knows it. And to be honest, it doesn't look like the Wings will be able to reprogram/deprogram of it him now either. I literally don't think he has the capability in him to adjust at this late stage. Jakub Kindl *was* a big scoring d-man but has simplified and adjusted his game. And while it's been very painful (much like Ericsson) he's show signs of starting to come around.
If your guy comes into the league needing serious defensive work, he's probably not going to succeed nowadays. And if he does, he will do so often at greatly reduced expectations.
This is all very interesting though. I think we're hitting on some of the many reasons why defensemen around the league aren't panning out well and why d-men are at such a prime price now.
(Andrew Alberts looks to be good 
even if you're not a canuck fan. 
