Well, for better or for worse, the NFL (when at it's best) is about winning And there is a body of work to say that, next week, Marcel Dareus is the best 1 tech DT or NT we can put out there and gives us the best chance to win.
Is it unfair to the people who put in there time, but didn't come in with as big expectations? Maybe. The NFL is filled with people who got passed over because someone had a higher draft spot and later prove themselves. But right now, this week, you play him.