The Celtics have shown and proven that there is a clear class difference between these two teams with the 76ers missing Ben Simmons. 
That much we know. The key question here is can Boston cover this large of a spread leading the series, 3-0? 
I do. The 76ers had their chance to win Game 3 and thus make it a series. But they didn't. They choked.  The 76ers blew a lead with 2:14 left. Despite outrebounding Boston, 20-3 on the offensive glass, getting Jayson Tatum in foul trouble and shooting 10 more free throws than Boston, the 76ers still lost by eight points. So they didn't even cover as 6-point 'dogs. 
Boston should play better. The 76ers are cooked - and they know it. No team in NBA playoff history has come back from a 3-0 series deficit. I don't trust the 76ers' mental fragility. I think they are badly outcoached, too. 
A double-digit Boston victory should be in the offering here.