I've not followed the upgrades Ferrari made to their engines over the season (and to be honest I don't have a clear view of how and when you can make changes), but I am wondering if Ferrari's reliability issues have come as a result of engine upgrades (not just replacements). It strikes me that in Italy Mercedes utterly dominated Ferrari, but all of a sudden in Malaysia and Japan Ferrari were able to put them under real pressure (as well as of course Singapore). They would probably have won the last two races if not for reliability issues. These things are usually put down to bad luck, but maybe they've been pushing their engine development too fast in a bid to keep up with Mercedes? I don't believe that three severe "power unit" issues in 2 races is purely bad luck... (Vettel Malaysia Qualifying, Raikonnen Malaysia Race, Vettel Japan Race).