Yeah, the system needs to be fixed. Instead of rewarding people for number of convictions, right or wrong, they should be rewarded for reducing crime by independent measurement. Or simply be rewarded for doing their job as honestly as possible, with proper accountability and all that.
But rewarding police and prosecutors for the number of convictions is like rewarding programmers for the number of lines of code. It rewards bad code and unjust convictions.
Maybe there should be a justice-equivalent of code review for police and prosecutors.