In the first months we were really lucky with the majority of games as well. As an example against both Chievo and Verona, we had about one shot on target and won both of those games 1-0. The second game against Carpi, they dominated us for large parts of the game. In terms of results, yes we were really good, but everyone felt the luck would run out and we'd start losing the games, which is exactly what happened from January onwards.
It's not just that we lost motivation, you don't lose motivation after being 1st on the table, but more of that we were playing the exact same at the beginning, except Handanovic wasn't making super-human saves at that point, so we saw the true nature of our team. I don't think our actual game-play was any different in the 2 halves of the season.