The APM program is a time limited (2 year) program that is fairly "up or out", in the model of McKinsey-esque programs.
If you're someone that Google has decided is an "up", I highly doubt Google is going to let these people go so easily. These people are already being aggressively retained with bonuses and the like.
If you're an "out", well, by definition Yahoo won't be that interested.
And the "ups" that "became outs", so to speak, are people who are of such strong personal conviction that they turned down gobs of money in 2007 from Google to, say, take a riskier position at Facebook or do their own thing. In those cases, it's unlike more gobs of money from Yahoo in 2012 will convince them to jump ship, unless Marissa can offer things to recruits that she couldn't offer to recruits at Google. (This seems unlikely - there was little Google couldn't offer the APMs it lost.)
Based on that logic, no good APM would ever leave Google. Somewhat surprisingly (apparently?), some people don't think money is everything and look at other things too.
Here's a pitch for you:
You can stay at Google, be successful and make good money. But here at Yahoo we have this search engine. We want YOU to make it better and more profitable than Google is. Look - we'll pay you plenty of money to come, but I'm sure Google will offer you just as much ore more to stay. But if you succeed in this role - which everyone assumes we won't even attempt - then you will be a legend in Silicon Valley forever.
Good bosses carry you long way forward. And this is not an understatement. Just look at what happened to the VP's in GE when Jack Welch was the CEO. They all went on to become CEO's of some very big companies.
You can go far in life by following a very successful boss. And there may well be more promotion opportunities / more responsibility available at yahoo under Marissa than staying at Google. Or perhaps they've already made a million or so and own a home; why not take a flyer and see where it goes? I think you massively underestimate personal loyalty to someone who it sounds like went way out of her way to look out for these folks' careers. Because if someone did that for me I'd be loyal.
If you're someone that Google has decided is an "up", I highly doubt Google is going to let these people go so easily. These people are already being aggressively retained with bonuses and the like.
If you're an "out", well, by definition Yahoo won't be that interested.
And the "ups" that "became outs", so to speak, are people who are of such strong personal conviction that they turned down gobs of money in 2007 from Google to, say, take a riskier position at Facebook or do their own thing. In those cases, it's unlike more gobs of money from Yahoo in 2012 will convince them to jump ship, unless Marissa can offer things to recruits that she couldn't offer to recruits at Google. (This seems unlikely - there was little Google couldn't offer the APMs it lost.)