Some very excitable HR newbies would like to drill down during the creation of performance management systems and make everything scorable on an employee's annual review. Then two things go wrong. First, managers don't want to spend a lot of time on each review so they push back on the shear volume of items to score. Second, employees cry "foul" when any items are subjective, which makes them ripe for abuse and favoritism. What is equally problematic, but rarely considered is the ad on TV by lawyers that specialize in helping employees exact revenge on bad bosses and bad HR processes. (Not that those lawyers are in any way evil. On the contrary - they truly protect wronged employees.)
Effective performance management systems are simple, valid, and reliable. Those traits ensure that they will be effectively used, will measure the attributes that matter, and will be objective.
So, what can you do with all of the subjective issues that impact performance? If you had taken the time to analyze the job (objectives, activities, and competencies), then you would know how to turn most of the "soft metrics" into measurable or observable ones. However, not everything turns out to be completely objective so you have to deal with those performance characteristics in another way. You must coach employees on those factors.
For example, how can you consistently and reliably measure tone and pitch on phone calls with customers? You could try to calibrate all company leaders who are responsible for measuring those attributes, but calibration never really gets everyone on the same page. Instead, you can either turn it into an objective metric by calling customers and asking them for their opinions (that is the only opinion that really matters anyway), or you can capture calls with questionable voice attributes and have coaching sessions with the employee. If you document the agreements and next steps/changes that were commited to after each coaching session then you start to create evidence of a pattern (either of improvement or a continued problem). As a coach you must help the employee identify how the problematic tone and/or pitch of his/her voice can hurt his/her ability to be successful. Once you get their buy-in you can almost always get them to hear on thier own calls how their voice may be preventing them from reaching their goals with each call.
So, if a metric is one of the seven most critical - in that it truly differentiates peak performance - and it is both valid and reliable, then it should be on the annual appraisal. Everything else should be part of regular employee coaching and development. If the negative behaviors are ongoing and a pattern can be documented, then it can be addressed as a performance issue.