Do not start from scratch and build something new regardless of what you already have. It is almost always better to improve what you currently have than to throw it all away and start over, although you should also be able to recognize when a complete replacement is, in fact, necessary.
This approach is not only less wasteful than starting from scratch, because it retains the value you already have, but also helps you keep your people engaged. They are much more likely to support the changes the organization needs if its previous contributions have been properly valued.
Do not rely on metrics and reports to tell you what the current situation is. When conducting an assessment, you should look at what is happening on your own and use metrics to support your observations.