I think what has affected felipe the most was the 2010 season. Even today he is still bitter about what happened in germany and even in singapore 2008. I think those things affect his head and even his driving. If it was some other driver like kimi they would have already forgotten about those things and moved on but massa still keeps on bringing those subjects up and sounds bitter. For such an emotional guy I think it has affected his driving. Then theres the accident and much spoken favouritism of alonso so is it really a wonder he didnt match up to alonso. There is no saying he would have matched alonso even if he was on top form but he would have made far less mistakes and been closer.
Also in years 2007, 2008 there was 2 top teams and the differences were bigger. Even if you had a bad race you might still end up on podium. After the reg changes there was no room for errors and bad stints easily ruined your race. And to me massa has always been average when he has been in traffic or otherwise have had some misfortunes. Drivers like alonso, kimi, vettel and other top tiers easily adapt to those situations but massa pretty often seems to lose the plot.
If williams indeed is a title contender I wouldnt be surprised if he upped his game. But in my opinion if someones going to fight for the title with williams it will be bottas. It amazes me how bottas is still under so many people's radar.
2010 does seem to stick in his craw. You'd think, given time, he would come to realise it was not an unreasonable thing for the team to do. You could argue, of course, that it wasn't allowed under the regulations at the time, and I'm sure some would argue Ferrari weren't given a serious enough penalty for that, but that's a separate issue to the one Massa appears to have, namely that he wasn't treated fairly by his team. I strongly disagree. Okay, the points gap wasn't that big between him and Alonso, but it was enough to mean he had no realistic chance of winning the title whereas Alonso had a realistic chance, albeit still an outside bet. That alone was reason enough for the team to want to maximise Alonso's points rather than Massa's.
Furthermore all the indications were that, without any intervention from the team, the points gap between Alonso and Massa was only likely to widen further as the season wore on. Even in Germany, Alonso was half a second faster in qualifying, which is a huge margin, and it wasn't even as if Massa had Alonso's pace in the race - he just had track position because Alonso had a poor start, so Alonso couldn't use the pace that he had. There was no reason to think Massa, had he been allowed to win in Germany, was likely to make any further inrodes at all into Alonso's points lead over him during the remainder of the season, let alone overhaul him, let alone challenge the Mclaren and Red Bull drivers for the title. Alonso was Ferrari's only realistic shot at winning the WDC so why on earth should they compromise that for anybody? If you want your team to give you an equal chance even when it's likely to compromise your teammate's title bid, you have to give them a reason to think it would be worth their while to do so, and Massa failed to do that. He should have looked at himself rather than blaming the team for his own shortcomings.