My whole approach to a struggling team member is to hope. I give it more time, tell myself they'll turn it around, find the kindest way to read every miss. Meanwhile the rest of the team has been watching the same problem for months, waiting for me to do the thing I keep not doing.
More people experience this than they realize.
Your plan for underperformance is to hope it improves while everyone waits.
If this sounds familiar, the Library can help you find the bigger picture.