Murphy is a spectacularly bad defender. As an 1x1 defender, at the 4, at the 5, as a help defender, in transition. Just too slow, lazy, soft and lacks awareness.
Overrated as a rebounder, he cleans his area very well but doesn't rebound out of it or above the rim - see how Indiana replaced him with 2 average rebounders and improved their team rebounding dramatically. One of those guys who boosts diminishing returns, gets lots of those rebounds that would end up in a teammate hands anyway. A good defensive rebounder, solid one overall, sure. But that's it.
Efficient but very limited as a scorer - not enough versatility in the ways he can score, not enough shot-creation skills, so he'll never be a prolific scorer. That wouldn't be a problem in Boston or any other contender. What would be a problem: the lack of scoring opportunities that would allow him to make a large enough positive contribution scoring wise in order to outweigh his negative contribution on the defensive end.
