Webmaster Tools data varies radically from Google Analytics

[Criscofur]

Hey everybody:

I have some weirdness going on w/ Google Webmaster Tools, and I wonder if it's happening to anybody else. In WMT, impressions and click-throughs started falling off a cliff in mid-April, and they've remained at a tiny fraction of what they typically are. Conversely, organic traffic in Google Analytics has increased (not at the same scale, but still). My question is, should I be worried about this? Or is it just typically questionable Webmaster Tools data?

Thank you!

[aakk9999]

In WMT, impressions and click-throughs started falling off a cliff in mid-April

Do you mean your total impressions and click throughs have fallen off the cliff or is it top searches you see listed that have fallen?

When you say "fallen off the cliff", what percentage drop are we talking about?

What I am getting at is - have perhaps your top performing keywords dropped, but you caught more long tail? Or was the drop in the summary of impressions/click throughs?

Another thought is - is there a chance that someone copied your website inclusive of Google Analytics code? This could overstate your traffic in Google Analytics.

And lastly - yes, it could be WMT bug. What does your overall traffic say and have you done some analysis of your logs?

[Criscofur]

Thanks for your response, aakk9999.

1) Total impressions and click-throughs;
2) Huge. From an average of roughly 12,000 impressions, 1,500 clicks/day to 450 impressions, 10-15 clicks/day;
3) Not according to WMT;
4) Interesting. No, I don't think so - I'm not seeing any alien pages show up in Analytics;
5) That's my next step.

I should mention that the drop follows (by about 3 weeks) a message about "a possible site outage" due to the supposed number of "transient soft 404 errors" Google experienced on the site. We recently redesigned the site, and there was some change in URL structure. All 301s are properly in place but that may have thrown a monkey wrench in the works.