Well I think it seems to be this way more than it actually is. Often times, if you lose points a few days in a row, and drop significantly in the standings then reverse it and climb back up, you would think that all your players are doing well or all are playing poorly, however this is not always the case. It has more to do with how close you are in catagories and such.
That being said I do think that teams go through streaks more often than one would expect and this is why:
Most people draft a certain style or look for a certain type of player. For example, a lot of people see late in the year which players are doing really well, and assume those are the best players. Often times, those tend to be second half players, so his team slumps early in the year and goes on a hot streak late in the year. There are also people who depend a lot on young players and rookies. As a result, they often are hot near the beginning when no one has really figured out these young guys, but tail off near the end when the effects of playing a full MLB season for the first or second time in their lives effect these young players.
2011 Live Free or DyNasty Champ