Sometimes there are honestly mismatched expectations or understanding of how performance is measured and evaluated. Other times, people assume new roles, and some aspects of the new role are not prioritized correctly or just not working out. I have witnessed some such cases, and personally managed one.
Working like hell does not help if the effort is expended in the wrong place. That's where the first 1:1 will be a clear indicator if the correction is working or not - if it's not working it may be a failure of a honest PIP, or PIP dressing up a decision that has already been made. But honest PIPs exist, and sometimes they do work to solve a problem that was not being solved by itself.
Any measure like a PIP is an attempt to reinforce a political/power structure. Where "mismatched expectations" indicate that it is not clear whether the behavior of the employee or the manager -- specifically, whichever manager has some part in that employee's success within the organization -- is the larger contributor to the failure to meet expectations. Most organizations are notorious for a systemic inability to distinguish one from the other, defaulting to laying the onus on the employee. So "working like hell" ends up as "effort expended in the wrong place." On the part of both parties. An "honest PIP" would be one where the intention is perceived as good, even though the need for a formal process is the result of some other weakness or failure where the net result is a less robust relationship, overall.
Working like hell does not help if the effort is expended in the wrong place. That's where the first 1:1 will be a clear indicator if the correction is working or not - if it's not working it may be a failure of a honest PIP, or PIP dressing up a decision that has already been made. But honest PIPs exist, and sometimes they do work to solve a problem that was not being solved by itself.