Maybe they were coasting
They paced themselves. They can't play agressive defense in the regular season because love, shump and kyrie are injury prone. Plus lebron has a billion miles on him.
So they pace themselves. Most great players pace them selves on offense and defense as they get older (jordan, kobe, magic, kareem and etc). It is just rare to see young players like love and kyrie do this. But with them being injury prone and not having a bunch of true defensive centers with height. Pacing themselves is the best thing to do to make sure they make it healthy to the playoffs.