I'd look beyond the traffic volume and check whether the intent of the new traffic has changed. It's possible to increase rankings and organic clicks while actually bringing in less qualified visitors. A keyword moving from page 3 to page 1 can look like a win in Analytics, but if the intent behind that keyword is weaker, conversions can still drop. I'd also compare the pages and queries that are gaining traffic against the ones that used to convert well. If you're also running paid traffic, I'd use the same approach with creatives: don't just look at CTR or traffic growth. Look at which message or angle is bringing people who actually take the next step. More traffic isn't necessarily a better result if the extra traffic isn't aligned with the offer.