They were pretty bad before getting s1mon too. They were losing almost every game at internationals and FPX was looking like the actual real contender at internationals from China.
Then they get s1mon and win champs and finish top 4 at Bangkok.
They kick s1mon and don't even qualify for the next masters, go winless at EWC and are looking bad now.
Its not about s1mon being the real winning player. He understood how to play with the team. Same case for Zellsis. Zellsis has never had a tourney where he was clearly better performing than Pancada, but he was the right fit for SEN's playstyle.