The feature that kept me engaged in BB where other online managers failed is that the game engine and the results it generates actually makes sense. Whilst upsets happen more often nowadays compared to when I first started, they almost always have proper context behind them to explain why one team lost. You won't see much weaker teams inexplicably win games like I used to see on other manager games I tried (Trophy Manager was a particularly bad offender).
This means that the manager has more control over their own destiny, as opposed to it being left in the hands of the dice shooter.