Perhaps it's a sign of what a good chief executive Eric Schmidt was at Google that I thought he'd spent just five years in the role.

When I remembered that Schmidt had in fact joined Google as CEO at the dawn of the new century, I was shocked. We were all so young back in March of 2001, untouched by nation-altering tragedy. Back then, Google was just an awesomely good search engine.

Schmidt, now chairman, shepherded Google from search to a network of wide-reaching and powerful services. As he noted during Thursday's announcement when Larry Page became CEO, Schmidt was the one that played the adult role at a critical time in Google's development. Without his discipline, what might Google have become?

I'm sure that Larry Page and Co-founder Sergey Brin had many big ideas back in 2001, but how to make them real, and how to bring it all together to create a powerful, vibrant and, most important, vastly profitable business would have been vexing, if not nearly impossible, without a seasoned CEO like Schmidt to show them the way.

Schmidt's button-down, yet affable style seemed to mesh well with Brin and Page's youthful "smartest geek in the room" approach – and there is no doubting their success.

Schmidt, meanwhile, must be credited with every major win, from AdSense to Picasa, from AdMob to Android, and Gmail.

It's a not a perfect record. Schmidt didn't always know how to quelch Google's backroom developer impulses. He let the Google Wave thing get out of hand and seemed unable (or unwilling) to guide Google Buzz to a gentle death.

Schmidt steps aside at a critical juncture. Google's made great strides in mobile, but the successful delivery of Honeycomb (Android 3.0) hangs over them. An industry is relying on Google. Without this made-for-tablets Android OS, it's unlike any Android tablet can compete with or beat Apple's iPad. Schmidt helped oversee the delivery of the very successful Google Chrome browser and the still somewhat confusing Google Chrome Operating System. The departing CEO will leave it to Page to figure out how far Chrome goes as a platform and if it ever merges with Android.

Ten years is quite a run as a chief executive, and Schmidt's legacy with Google is assured. Now we'll wait to see how Page will run the company he cofounded, and where Schmidt will go from here.