Performance review goals in a highly mutable environment
BLUF: How do you set meaningful goals in an environment where roles can fundamentally change several times in a year.
My employer is introducing performance related pay and giving annual reviews (that previously few managers have bothered with because they have been meaningless) teeth.
This is causing some concern in the business unit I'm in as our environment can be highly mutable. We're essentially an internal consultancy and can be placed on projects for periods ranging from a few days to a few years. Our only work is on projects, we have no 'day jobs'. When not on placement we are 'on the bench'. Whilst most people will only have two or three placements a year, 5+ is not unusual and seven to nine is not unknown. The roles a person is placed in during the year can vary quite widely so, in particular for someone like myself with a very wide skill set to offer, the skills used, and therefore objectives acheived, on one project can be very different from those on another.
The concern is that someone might be set objectives one April (our year matches the financial year for reporting reasons) that are not relevant to the work they do for much of the year so they don't acheive them. Also someone might spend a long period on the bench because there's a shortage of roles and not have the opportunity to acheive their goals. Since this is the result of things outside their control it is considered unethical to hold them responsible for the result.
These concerns are coming as much, if not more, from the managers performing the reviews as they do from the staff subject to them.
Does anyone have any experience of a similar situation? What would be the best way to resolve this without going the route of setting very vague goals that could be satisfied in any roles?