On the pregame today, Ned Yost said (and I'm paraphrasing here) that one of his strategies on how long to let a starter go is to not let his starter have the opportunity to lose a close game after six innings. That's all fine and well and when you have a great bullpen, which the Royals seem to do the strategy makes a fair bit of sense.
Here is my thought though, if a starter is dealing why would you pull him just because you want to ensure he doesn't blow his own win opportunity? Do teams pull Roy Halladay, Justin Verlander, or other starters just because the going gets tough and they could lose the game? Obviously, the Royals don't have any starters of this caliber, but will the strategy change one they do? (fingers crossed)
If you aren't comfortable allowing your starters to pitch deep in close games just because their win is at stake, you aren't doing your bullpen any favors. Sure Kansas City's pen is strong and deep at the moment, but they lead the Majors in innings pitched and it isn't uncommon at all for pens to lose steam as a result of logging to many innings.
The strategy may make sense with the current roster, but I'm not sure if I'm a fan of instilling a 6 inning mentality among the starters. In my opinion if a pitcher is on a roll and isn't showing signs of slowing, the length of his outing shouldn't be determined by the offense's performance. This team severely needs an innings eater and it is hard to do that if anytime the game is close after 6 the pitcher is likely to be pulled.