Ted, a senior employee, believes he is underpaid and attempts to compensate by routinely keeping short hours, though it is obvious to everyone that he still makes some valuable, unique, and perhaps irreplaceable contributions.
Decision
Ted should not be replaced.
Evidence
It's obvious to everyone that Ted makes some valuable, unique, and perhaps irreplaceable contributions.
Evaluate
Usually for Strengthen-Principle questions, we just predict an "If Premise, then Conclusion" link, so in this case that would be something like
if X obviously makes then you some valuable, unique, → shouldn't request or perhaps irreplaceable that X be contributions replaced
However, the final claim is prefaced by Nevertheless signaling the tension of Tatiana deciding to keep Ted, given that we were told he does have some deficits in his performance that other coworkers have to work harder to compensate for.
When we're doing Strengthen-Principle and we see that the argument is wrestling with a positive and a negative, then the answer will often feel more like it's Weighing Tradeoffs.
Goal
Look for the linking idea we predicted, or look for something saying the positives of Ted (valuable, unique, possibly irreplaceable contributions) outweigh the negatives (a deficit in performance that other coworkers have to work harder to make up for).