At this point, I would say the answer is yes. It doesn't matter whether a guy plays through injury. He is injured nevertheless. But what it is called doesn't matter as much as what the impact is. At this point I would say that unless there is something significant that changes his physical condition, he can remain elite with the glove, but forget any GG awards at 3B going forward with the unreliable, lolly pop arm. He looks like a guy that will be at 3B for another year (or two max) and then become one of the best fielding 1B in the league.
After watching the AFL Rising Stars game, even though I didn't get to see Rendon field, I'm starting to think that this is what the Nats will do. Rendon looks like he will rake at 3B and sounds like his defense is top notch. Probably why they haven't forced him off of third yet.