Is it better to have a player who scores 10 points every week or one who puts up a goose egg one week then drops a 20-spot the next? There's no perfect answer, but depending on the overall strength of your team, it's something to consider. If you have one of the better teams in your league, you want to be starting consistent guys. If you are trying to make up ground, then starting a boom-or-bust player is probably your best course of action when you are playing the better teams.
Measuring a player's consistency does not need to be rocket science, but it does involve standard deviation of weekly scores. Don't worry for you non-math geeks; I've done all the work. First, I discounted the impact of turnovers on weekly scores. In my opinion, turnovers are just as much the product of luck and game situations, and thus unfairly penalize those with more touches. Next, I take the player's revised average weekly score and divide that score by the standard deviation of those scores. The result is the player's consistency rating. Keep in mind that the higher the number, the more consistent the scoring for that player.