Help Center has been updated with a new look and navigation system, and the dashboard in your AdSense account has been updated as well.
Recent additions include the Scorecard, which for some people seems to have created a small panic. The Scorecard really is just a way to see where you might be able to improve your site(s), and your AdSense earnings or traffic. Suggestions made in the Scorecard are just suggestions.
Just as an example, if your "Revenue Optimization" on the Scorecard shows less than 5 blue dots, you can find out why by clicking the little down arrow next to "Revenue Optimization". The sections listed are "Recommended Ad Formats" (are you using all the most recommended ad sizes and formats?); "Text and image ads enabled" (have you enabled all your ads for text and image?); and "Crawler Errors". All of these subsections will have a green checkmark, a yellow exclamation point (recommends changes) or a red exclamation point (needs work). The small arrow next to each section opens up to display their recommendations.
Most successful ad sizes.
So what do you do? The first thing you do after reading the information is really take a look at your own site - you know it better than anyone else. Consider why you are currently using the ad sizes/styles/formats that you are using right now. You chose them for a reason. What was that reason? Was it the same when you chose them as it would be now if you were putting new ads on your site?
Recommendations aren't always right, so it's up to you as the site owner and publisher to think about what works best for your site and for your visitors. Don't arbitrarily make changes to ad sizes just because Adsense says you might earn more. If your site's size (in terms of screen width) can't support larger ad units, don't use them just because Adsense automatic suggestions think you should.
Most site owners who have an interest in providing a good experience to their users will first consider how the larger ad units might affect that user experience, and whether or not larger ad units actually fit well into the ad space provided. If your site appears to have too much space taken up by advertising, then using larger ad units is probably not a good choice to make.
Don't blindly make changes that Adsense suggests to your site - keep in mind that these suggested changes are basically "auto initiated", so nobody physically has gone to look at your site. That much is apparent when it's been suggested I use a 970 pixel wide leaderboard on a website that is only 800 pixels in width - it seems rather obvious to me that an ad that large simply won't fit across the width of my site so I'm certainly not going to institute that change.
The same can be said for all the suggestions made in the Scorecard - you should fix things that actually require fixing (crawler errors), and you should review their recommendations and suggestions, but don't panic about instituting those changes if you are happy with your site layout and/or can't make all the changes they expect.
In my Scorecard under "Site Health" (Page Speed Performance) there is always a yellow exclamation point. Why? The pages they list for recommended change include a website that includes articles as well as a lot of free images and textures, they expect me to reduce the image weight so the images will not slow down the page load time, but ... well, it would be pointless to optimize the images to the point where they look crappy. I'm a photographer, I don't want my images looking bad so they load super fast. All of my images are already optimized for web, and they're optimized to a level I can live with. I'm not going to optimize them any further just because Adsense thinks I should. They're not the one whose reputation is on the line, I am. So I'm the one who has to decide that, not Adsense.
The other page they list as a slow loading page (it isn't slow, actually so I have issues with that but ...) is a blog hosted on blogger. All of things they say cause the slower load are (a) blogger coding and (b) adsense ads (only 2 on each page, and no other ads). I guess they want me to fix the Google issues?
So having taken the time to review their recommendations I decided against taking them, and left my pages as they were. None load so slowly that it's an issue, and making whopping changes to get a page to load a few nano-seconds faster isn't really worth the time, nor the issues that would be created by making those recommended changes.
Having five blue dots on the Scorecard isn't my goal. My goal is to provide useful information and products to my visitors, and I believe I'm doing that reasonably well on my monetized sites.
In the end, it's really up to you - the site owner - to decide which changes make sense for you, and which do not. Your decisions should never be based on the fact that "you are losing revenue", because you may not be losing any revenue at all. In fact, sometimes making the recommended changes may cause you to see lower revenues than you previously had.
Approach any changes to your site with thought and consideration before running off and making major changes.
Help Articles for the Scorecard
About Your Scorecard: https://support.google.com/adsense/answer/3006004?hl=en&ref_topic=3131279
Changes to Your Scorecard: https://support.google.com/adsense/answer/3131280?hl=en&ref_topic=3131279
Coming in the next round of Update Articles - Signing Up from Blogger and YouTube, Resubmitting Applications with a new URL, and ASense Accounts from an AdMob Upgrade.