Andy still won 3 titles this year despite post surgery comeback and having to deal with players who have just peaked this year (Wawrinka, Cilic, Nishikori and Dimitrov to lesser extent) and that's still better than Federer's 1 title last year in Halle. So we can't afford to write the season off. Andy needs to focus on what worked for him this year the most and take it from there.
Federer tends to play some of the tournaments the most because he's won them the most and he's most comfortable there and the confidence factor just works out for him automatically there in those tournaments (Halle is one of them). If you research Federer's resume enough you will notice the trend.