Part of the Job
I have to agree with the basic premise of the article -- after more than 13 years of managing developers, a manager has to understand the reality that "staffing" part of the job includes the occasional termination. I see this from a few angles, because I can confess that, in my earliest years, I really didn't want to go down the termination route. It's as stressful for the manager as it is disruptive for the team.
A good manager will bring a new employee onboard (including transfers from other groups) and spend a lot of time discussing how the group works and spending particular time on the new employee's responsibilities and initial objectives. It's necessary from the very beginning to spell out the requirements of the job (as was done during the interview, I hope). This is important not only in making sure that the employee knows exactly what you expect, but also to ensure that the manager is covered should something less than optimal occur later on. The manager should also take particular care to document the content of the discussion, date it, and save it in the employee's file. If you go down the performance improvement/warning/termination route later, the documentation will be crucial.
In the end, the manager's primary responsibility is to the team and the high performers on the team (even if you can't always pay them everything they're worth, you can show them the respect they deserve). If an employee isn't performing, the manager should take steps to understand why the situation is occurring and try to correct via training or different work assignments (up to, and including, a transfer to another area where they can perform well).
Once an employee has had ample opportunity to identify and improve the weak skills, but they still either can't or choose not to improve their performance, the manager has little choice but to take addition steps up to, and including termination.
For the manager, always keep your manager and HR informed of performance situations. Make sure HR is involved from the very beginning, and take their advice to heart on retaining the necessary documentation and having the right discussions with the employee at the right time.
Bottom line -- Priority 1 is to protect the high performers. Priority 2 - make more high performers. If you can't either be a high performer or be moving toward high performance, you're in the wrong job and the manager should follow-up as quickly as possible.
