Big reduction: indexed pages, structured data items, pages crawled

[ccollector]

While it doesn't appear like we have more errors or specific problems, there has been a big reduction since mid-Feburary in number of pages crawled, number of structured data items, number of indexed pages.
As the website uses responsive design and offers exactly the same urls/data for mobile and desktop, we shouldn't be affected by the Mobile-first switch.
Previously the numbers were growing slowly, but since mid-February we've lost around 200k structured items, 6M indexed pages and around 3M crawled pages per day.

Are there any other Google changes that could affect the stats in the past 2 months? I've looked through the discussions on this forum, but haven't found anything that could be relevant to our case.

[goodroi]

Google has been tightening their indexing quality standards since last year. Actually, Google has always been doing this but since last year they have been moving at a faster pace. For many webmasters it can be hard to notice unless you are working with large data sets and then it is easier to notice this trend.

I suggest you start by revisiting your templates to ensure you are publishing a sufficient level of unique value per page. Near duplicate pages are most at risk. The good news is that this drop in indexing usually doesn't impact a site's traffic too bad. I would still encourage you to audit your site and boost the value proposition because most likely things will only get harder.