Similar to How to deal with a bad coworker but my case is not about behaviour but rather about incompetence.
Context: Our team is charged of designing and developping reports for the finance department.
I am wondering how to deal with all impacted stakesholders regarding this situation at work where a coworker has done a significant amount of very poor quality work and now I have to use his work to produce reports for our colleagues. That coworker is still in our team but he is not in charge of these reports anymore. The other departments are aware that the work was previously done by my coworker and that he did a poor job.
Now this is a great opportunity to show that I can greatly improve this tool but since this is a very large amount of work it will take some time and for now there are issues of formating, data integrity, the overall process and the amount of time it takes to both maintain and produce the reports.
How can I appropriately deal with this situation so that the other teams know the issues I am currently facing but cannot fix right now are not the result of my own incompetence but rather of my coworker's.
TLDR: How can I make sure that poor quality work from a coworker does not impact my reputation without going around and telling everyone he did a poor job ?