Coaching for performance is the preferred option to deal with underperformance and is the first step in addressing performance issues.
A manager has to wear different hats while carrying out their role as a leader of a team. One of them is to be a coach. The coach differs from a "supervisor" or "leader" or "mentor" in the underlying belief during their conversations with their team. The belief is that, the team member knows how to solve their problem and should be given the autonomy to do so. The gap to be covered is to remove the confusion that is not allowing the team member to objectively see the real issue.
To this end, the manager works on identifying their own biases and emotions clouding the conversation. They do the work of getting to a position of calmness and neutrality. They then approach the conversation with a questing attitude of asking open-ended questions, where the team member finds their way through the confusion, to solutions they can own. This increases the sense of power over and ownership of the solution in the minds of their team members and they feel empowered to take the solution to its logical conclusion.
The manager identifies the right performance concerns (poor results and/or behaviour issues) in a timely manner.
The manager builds a case for intervention, using data, timelines, and impact on the project/ team members/ organisation, of the underperformance. They are able to keep out judgment and biases.
The Manager invites the team member into a scheduled one-on-one meeting. They tell the team member that the intention of the meeting is to find facts causing the issues on hand, and solving them together.
The conversation should be documented by the manager with permission of the team member so that both of them have a record of the discussion and are in alignment on where improvements needs to be made and by when.
Documentation should be brief (a few key bullet points or a paragraph of the challenges shared by the team member, common agreement on what the issue is), and should be shared with the team member within 24 hours of the verbal discussion.
Helping the Obvious team-members understand clearly the larger impact of their performance on others and on themselves, is very important to foster greater awareness, ownership and energising immediate improvement and continued success.
It is also important to clarify when feedback given can provide helpful coaching vs. when to address a serious performance or behavioural issue. It is not always clear how serious the feedback being provided is and setting the context can be critical. If there are extenuating circumstances, some leeway may be granted, depending on the situation. This is an area where someone in the People Ops/Exec team can provide a sounding board or voice of reason.
When underperformance is detected, managers should compensate by checking their report's work more frequently, on a mutually agreed cadence.