Since 1988 home teams in the conference semi-finals are ~33-18-1 ATS. A week off this time of year and not having to travel gives home teams in this spot a big advantage.
out of those 18 times the home team didn't cover, would you know how many lost straight up? it seems to me that the home teams wins most often, and the spread barely comes into play. therefore i think if you take the underdog, your best to take them on the ML.