Based on your own experience, what is the most serious weakness in the performance review process?

There are advantages and disadvantages with evaluation tools, depending upon what is being measured and how the tools are implemented.  Sometimes, the weakness in a performance evaluation process can be remedied by selecting a more suitable tool, to address the criteria being measured.  However, even the most appropriate tool will render less-than-best results, if not properly utilized.  Read the information at the links below before responding to the discussion question this week.      Interesting insight into performance reviews: http://online.wsj.com/news/articles/SB127093422486175363   Another one: http://online.wsj.com/article/SB122426318874844933.html   and: Interesting Article: Get Rid Of Performance Reviews? Sure, But What Do You Replace Them With? http://www.eremedia.com/tlnt/get-rid-of-performance-reviews-sure-but-what-do-you-replace-them-with/     Based on your own experience, what is the most serious weakness in the performance review process? How can it be changed?