Quality of depth. Apart from losing Votto for a stretch and the Madson debacle, the Reds never had a key player miss significant time last season. There's certainly no guarantee of that happening again, so it may come down to what saved us during the 2010 season: having players on the bench that can step up when the injury bug sets in.
We're getting an influx of new blood on the bench (no more Valdez and 2012 Cairo at least), and our rotation goes quite deep, but I'm a bit skeptical of the bullpen. I get a feeling we may have to pull a Louisville starter into a pen role by the end of the year due to injury or underperformance.