I haven't done deep data on it, but looking at the past five years, the two semifinal games have been decided by an average of 12.8 total points, or 6.4 per game. Lots of thrillers there.
You have to go all the way back to 2010 to find a bonafide blowout. In the handful of games (I think I counted 3) since 2010 that have actually gone double-digits, it was always because of a team pulling away from a close game at the FT line.
This year's first round and most of the QFs were blowouts. The SFs separates the wheat from the chaff. That's why for years, no matter how tired I was (like yesterday, having started the day at 8am and worked 2 jobs), or hungover I was (a regular occurrence when the SFs were a morning thing), I always drag my sorry behind to the SFs because it's always great ball.