I don't think the drop off we saw at the tail end of last season can simply be explained away by "nothing to play for". I might be wrong but I don't recall playing like shit and losing being a noticeable feature of many title winners. Either way, it shouldn't be accepted.
As for Salah, I think there are two sides to the situation right now.
On the one hand, we've got one of our all-time greats who contributed to massively to one of our best periods in a long time and for many younger folk, the best they've seen.
On the other, we've got a player that by all accounts we had to fight quite hard to keep (basically empty our wallet). At the moment, that is feeling like a very one sided transaction. You can argue that the game is the game and he's looking out for himself but then... if we're treating it as just business, that goes both ways.