Williams dropped the ball a bit, they should've either told Massa to let Bottas pass or pitted him for the undercut. Hard call to make though, telling a driver to give up the lead, and would he comply? He didn't want to give up the place in Malaysia, (2013 or 2014) and that wasn't even close to the podium positions
Theres a small rain cloud potentially about to clip the circuit and then a big one coming in 20-30mins. Williams have the slower car so you can't really blame them, the only thing they could have done is split the strategies. Leave one Williams there to block the Mercs.