This would probably be captured when looking at GA in the landing page report with MoM traffic going to 0 for once high value pages. If that is the case, a 301

This would probably be captured when looking at GA in the landing page report with MoM traffic going to 0 for once high value pages. If that is the case, a 301 from old path(s) to new is the simplest solution to possibly restore most of the traffic? From what I've seen, lots of the SO scraper sites got crushed late last year, so if the top traffic driving pages historically have not had URLs changed, then maybe investigate that further. If they had their URLs changed, just redirect the old URLs and hope for the best. @OP, if there were in fact high traffic pages that got renamed, do a CSV/Excel export in GA/GSC/sitemap/etc., and map the old URLs to their new and implement 301's and wait and see if traffic starts to return.