By all the struggling of the previous two series, the Celtics should be through underestimating opponents by now ... that lesson should have sunken in, and they should play from here on out like they need to, with the appropriate "playoff" intensity, and the determination that they've shown throughout the regular season. That said, I imagine that like any team, they will still have a let-down or two, and that how they recover from such, and how quickly they take up the slack, will be the key.
We all know that Detroit is the type of team who thrives on exploiting the weaknesses of their opponents, and their number one weapon against the Celtics will be just that: waiting for them to let down in some area and attacking that soft-spot. However, if the C's are smart, they'll keep the tempo up on the Pistons and force them to take up the slack, thereby not giving them the time or opportunity to gain control, or bring things down to the "grind-it-out" environment that they thrive in.
There's no way Detroit can run with us consistently, and that should be the number one focus for Doc and the boys ... that and the stifling defense, of course. The Pistons' true advantage over the Celtics lies in their confidence, and the fact that they've been here many times before, while this present Boston team has not. That can be exploited, though, and could actually be their undoing, if they end up taking that advantage for granted.
A running, attacking team can turn that "cockiness" around on a veteran team, by just plain "out-hustling" them. A surly, experienced team retains their confidence by playing "their" game ... controlling the tempo and setting up their plays. By running and attacking, you keep that team on it's heels, and don't give them the time or opportunity to get their defense set-up, or run their plays effectively.
If the Celtics slow down and let their weariness/fatigue lull them into playing a half-court game, the Pistons will have them right where they want them, and the tide will turn. The odds are actually in their favor by being a half-court team, because everyone and every team has the propensity to want to rest, especially if they've been running consistently, and a half-court team like the Pistons is just laying-in-wait for that to happen, so they can gain control and turn the lack of energy in their favor.
If I thought the Celtics would maintain the attacking "up-tempo" game, and sustain the defense that has gotten them so far, I'd say this would be over in four games ... easily. Unfortunately, as they've shown so many times before, and as a "new" team has a tendency to do, they can sometimes be their own worse enemy, and often get caught-up in playing a half-court game themselves, even though they know how disadvantagious is it for them to do so. That's what Detroit wants, however, and they've got to refrain from slowing down as much as possible.
I honestly don't think the Pistons are as dangerous, or even as good, as many people say they are ... unless you play "their" game. If we can avoid slowing down to the half-court, sustain the run, keep attacking the basket, and play our best defense, I have no doubt that we'll get through this series in less than 7 games. It's all up to us, as it has been in the previous two series, and depends on our ability to recognize what is our and our opponent's strengths and weaknesses, and utilize both to our benefit.
The biggest problem is that Detroit has had much more time and experience at doing these things than we have, and is smarter overall as a result. It's not rocket science, however, and if we just keep our heads and play smart, we'll be fine.
Go Celtics!