As you can see, the low turnout in the 2015 election affected all parties but PaF suffered the most. Many PSD and CDS 2011 voters didn't vote for them in 2015 because of the austerity policies the coalition implemented during the Troika years. There was also some vote swings to the PS and the Left Bloc, which in this case are, probably, many young urban voters that were pissed about youth unemployment and lack of opportunities.
The coalition lost around 700,000 votes in 2015, they would always lose some voters but they would benefit because the electoral system helps coalitions. But if you add the gains, in votes, the PS, the BE, smaller parties like PAN or PDR and the abstentionists had, you will have a number that almost matches the number of votes that PaF lost in the 2015 elections.
This is right but not justify your affirmation that they win the election
