Who do you think was the worst player on the pitch against WestHam? Mahrez by a country mile, right? The conclusion that you drew from that match cannot possibly be that the other 10 City players let him down. Every single one of them was playing on a higher level than he was. We've got to agree on that, surely.
I'm not sure any player gets more or less help than his teammates at City. Everyone works for the team. Everyone pressed. Everyone passes to the open man. The team isn't the reason Mahrez continually misplaced his passes or got weight wrong. There's not much you can do as a teammate or as a coach in Guardiola's case, when this happens.
Bad matches always happen. So that's normal. But what's worrying is that the West Ham match wasn't a one off. He has been poor for a while, hasn't he?