Putting all the normal "Bruce Arians sucks" or "Arians can't call a game to save his life" responses on hold for a minute...let's focus on why this seems to happen.
There aren't many people that can offer up legitimate gripes about Arians' play calling inside the 20's. He uses the passing and running game well. Last week he broke out the SB XL WR pass play for example. The Steelers are generally able to move the ball against virtually any defense. Sure he occasionally calls a bonehead play but overall when the Steelers want to move the ball, they can.
In the redzone however, this team just goes into a mode that makes me scratch my head everytime. As soon as they hit that part of the field, they take their foot off the gas and go into a completely predictable set of play calls. They seem to be stuck in this mentality of "this is a game of attrition", "we have to run the ball to assert our dominance and break your will" mindset that just drives me nuts.
Who cares how you score a Touchdown!!! Just get in the damn endzone! Don't just lineup and run 4 times, use your imagination for once. Thank goodness in that game last week he finally used Mike Wallace on the quick fade which was money. Where is Heath Miller in the back of the endzone, where is Hines in the back of the end zone, where is the Tackle Eligible pass, where is the designed boot leg? It takes this team being stopped inside the 5 and settling for a FG or no points at all before they realize, "oh maybe we should try something else"
If you are going to run it, why aren't you using your short yardage specialist in Redman?