With Alonso returning to Renault, I think the main problem was that the only competitive teams at that moment were Ferrari, McLaren and BMW. Ferrari and BMW were both happy with their line ups and saw no reason to replace either of their drivers. Alonso’s best option was Renault, who were the best of the rest.
Alonso stayed with Renault hoping they’d build on their good form at the end of 2008, which unfortunately didn’t happen. He could have joined Honda/Brawn, but Honda were poor at the end of 2008 and that is most likely why Alonso join them in 2009. I think Alonso could have joined BMW, with him replacing Heidfeld. However by the end of 2008, Renault were faster and Heidfeld was beating Kubica again, so BMW gave Heidfeld a new contract.
Giancarlo Fisichella joining Ferrari wasn’t a great move. He and no one else though could have known how difficult it would have been for him however. Yes Badoer couldn’t adapt to the Ferrari, but it Badoer, Fisichella was way more accomplished than him.
Glock joining Virgin wasn’t great move either. At least Kovalainen and Caterham, they seem to be getting closer to the midfield, but Marussia aren’t showing any signs of getting closer to Toro Rosso. You wouldn’t think after he stood on the podium at Singapore 2009, that halfway into 2012, that would still be his last points finish.