JR was a menace on defense in 2015-17. He did as good a job as any player defending Klay and was used mostly as a pure spacer on the court. As we know, the more contested his 3pt attempt the more likely it was to go in. He made a few boneheaded moves here and there as JR is wont to do, but he played the best defense of his career during those years.
Love was a really good player in the first 3 rounds but was always a bad matchup with GSW. Steph and Draymond were always exploiting him on the defensive end and he wasn't able to consistently punish them back on the other side. You could argue that the only reason we won game 5 of the 16 finals was because we were forced to run RJ at power forward which gave us a much better matchup with the death lineup (especially after Bogut went down). Having 4 switchable guys + Kyrie matches up much better than 3 switchable guys + Kyrie + Love, even if one of those guys is the best version of LeBron we have ever seen. I will give Love a ton of credit for showing up in game 7 with his excellent rebounding (13 boards) and surprising defense (you know the play), but I am not sure we make it to game 7 if he had a highly featured role in games 5 and 6.