See, I think 54 games is low, but I don't think it's THAT low. f I were guessing, I'd put the over/under at about 57.
I fully expect it'll take a while for KG to get back to being KG, and that he'll be held out a fair number of games (if the knee gets sore or starts tightening up, they'll hold him out).
Given the ages of Paul and Ray, I think you've almost got to expect that they'll miss a few games here and there as well. They won't push it, the mission will be to get into the playoffs as healthy as possible, so we'll see plenty of games where they're only on the court for ~30 minutes, and they'll also err on the side of caution when the inevitable bumps and bruises start to accumulate.
As to last years' win total, we began the year absolutely on fire, I'm not sure it's realistic to expect THAT kind of start again; just a more normal start to the season and you're looking at a few less wins.
In general, though, I think they're going to be a little more on cruise control - get through the season intact, try and ramp things up later in the season but don't kill themselves and burn themselves out going for the #1 seed.
So, 57 sounds about right to me, and if Paul or Ray misses any significant amount of time (which has to be considered a risk - not an absoloute, but a risk), there's still a pretty steep talent dropoff still to Daniels.