Is it harder to stay on top than get there? (By top, I mean competing as a top 5 team in the nation on an annual or nearly annual basis.) I think the challenge is more psychological than physical...and perhaps that's what's makes it harder. Defeat has a way of sharpening the senses and creating an urgency (in competitive programs) that runaway wins do not. When your not challenged, it's nearly impossible to keep complacency from setting in...with players and coaches and fans. It's human nature. The natural tendency is to become less hungry, less focused. (LSU had that same level of focus that we had against Fla. in the 09 championship game and LSU last Jan...Both of those efforts were aided by prior losses to them.)
I think this is what makes Saban's tenure all the more impressive. The recruiting restrictions have leveled the playing field from the old days, and yet he continues to field a motivated, top tier team, year in and year out.