I think it's absolutely normal for someone to get disenchanted, or more or less, bored with fantasy baseball at this time of year. It's August and you have a clear picture that you're out of the running in your roto or H2H league for that matter, for instance. With fantasy football right around the corner, and for some folks heading back to school while some folks are working 50-60 hour work weeks, there's a high degree of burnout that can result.
I'm more disenchanted with fantasy football actually, rather than fantasy baseball, and so it's the complete opposite with me. I have my reasons, but I find the marathon of fantasy baseball more satisfying than with fantasy football, which feels like a sprint every Sunday. Fantasy baseball requires a great deal of daily commitment whereas in football, it's a weekend activity, as glorious as taking in a college or NFL game. Personally, I'm pretty much behind in my preparation for football getting ready for a handful of H2H playoffs, which is just as fun as prognosticating rankings and player projections in Spring Training.
Besides, I consider myself to be more of a die-hard soccer fan than football or even baseball fan and am more hyped with the Premiership in England already a match or two in and La Liga in Spain this weekend. On the side, I have 4 Premiership fantasy teams and 2 with La Liga. Fantasy soccer, if you haven't tried it, is like fantasy football, but it's a long grind given you have 38 gameweeks, as opposed to 17 gameweeks in football. It's the best of both worlds really.
Am I feeling burned out by fantasy baseball? Sure. Am I bored? Not by a longshot.