On the one hand, I can imagine being frustrated with a similarly strong lineup that is struggling along at .500.
On the other hand, the more I think about this small sample/random deviation issue, the more I come down on Mike's side regarding the need for statistical variation over samples of game even over 160.
One beauty of this is that you simply don't know what could happen over a season, and that gives you hope no matter what your team looks like. Pick up any big league daily in late March, and you'll find articles about how the Royals, Brewers, White Sox, Tigers (well, not the Tigers) COULD CONTEND if everything breaks right. Well, the same thing applies here. It gives you a reason to play the games and try to manage your butt off. Yet, just as in real baseball, the teams that do win are 1) the ones that amass the most overall talent (e.g., Cleveland, New York) or 2) the ones that amass the most COMPLEMENTARY talent (e.g., Atlanta, Boston). So, in your GM role, you also have motivation to try to accumulate good young players and veterans w/ some years left as well. The more talent, the more options you have when things don't go as planned - just as in real baseball.
One final point on the small sample frustrations.
My B8 team last year was pretty solid, and I expected them to be able to win 88-92 games, in part due to a weak division. At about the 75 game mark, I was 17 games under .500! I traded a couple of good players to get help for next year, but kept the core of my team. The team won 34 of the last 41, beating teams we had no business beating, and tied for the last wildcard spot. The team defeated two stronger teams in the playoffs (you never know...) before getting trounced in the series. It was the most satisfying season I've had to date playing the game, in large part because I had the patience to wait out a 75 game "small sample."