He says that, most often, good practitioners focus on their own performance and their own personal targets and goals, and that does not necessarily reflect their ability to manage and lead people.
Good practitioners can be intimidating as bosses, occasionally they can become workplace bullies. Walker says: "They tend to hold themselves to a high standard. And if they are the best performers in an organisation, more often than not others won't be able to reach those standards and they're not forgiving if they don't.
"That's not all - but you can see why organisations think: 'We have Jack or Jill and they're fantastic at what they do, wouldn't it be brilliant if we could clone that person and their abilities' and so they automatically think: 'Let's promote them, let's put them in a role so they can recreate that'.
"Someone who is a good practitioner is often ambitious and will welcome the opportunity, but they don't always invest effort or time to become a good manager. They still focus on their own performance and targets." He says this can become detrimental for the company.
So what makes a good manager?
"I've simplified it to three areas. One is ability to provide direction, and that's either through a vision, strategy, objectives, or goals; secondly it's the ability to motivate and create an engagement and commitment within your team.
"Thirdly, and the biggie, is the ability to coach and develop. This is something many companies don't do well. In the NZ market we see a lot of 'training and telling' as opposed to 'training and coaching'. Training and telling someone is: Now that you know how to do it, just go and do it -- without any evidence that the person has learnt those skills or embedded them to create more capability."
Walker says what a coach does is gain evidence through watching the person perform on the job to see that they have the capability to do that role or the capability to improve. This tends to be the missing ingredient in management. "Train, coach and motivate is what's so important."
Not everyone has this level of people skills.
Emotional intelligence is the ability to read people and personalities and also to know at different times and circumstances you may have to act differently.
So if you've got a staff member who is going through grief, for example, you know not to have the same level of expectations than when you know they're fine.
"That's why I break it down to three simple factors: motivation, direction and coaching. You can have someone who is highly capable who is not performing well. That could be because they haven't been given good direction, or they may be demotivated or disengaged and it may not have anything to do with work - it could be something that's happening externally.
They might need some different type of support to get them performing to their potential again and it takes a good manager to be able to talk to their team and to discover and understand which of the components they need to work on to supply that support to get that person functioning to their best ability again.
How does a company choose a person for management if doing a good job as a practitioner isn't enough?
Walker suggests a long-term approach. "You need to look at what tasks the person you're promoting needs to be able to perform . Then there needs to be a reflecting on how good or how strong the person you're looking to promote is at those tasks.
"So, really assessing that individual against those specific tasks and having some evidence, not just an assumption, that they're good in these areas. If they're not, perhaps they need some coaching."
Walker says if they don't achieve what's required through the coaching, perhaps a different pattern of rewards needs to be given for being a good practitioner, rather than being promoted to manage people. "Giving them more challenges, and better remuneration may be the key."
It's about deciding someone's going to be a leader, and then mentoring and coaching them long before the actual promotion.