The Pittsburgh spike was double stupid. Not only did they waste the down, but they stopped the clock.
There's no way you want to stop the clock in that position -- keep it moving or make the Ravens use time outs. You want to be in the position that if you kick a field goal, you do it with no time left on the clock. Well, not really -- you want to kick with about 15 seconds on the clock. You don't want to risk a false start or something and a 10 second run off.
As soon as I saw Pitt get the first down and stay in bounds, I thought "perfect." Take it down to about 30 seconds and run your first down play, leaving Baltimore no time left.