While Nettles only won 2 Gold Glove Awards in his career, it's not hard to figure he may have been able to win more. Over 2412 games at third base, Total Zone had Nettles worth 136 runs above average at third base, although he was no longer above average after 1981. Still, Nettles was a great defender both statistically and anecdotally. He brought a lot of value to the Indians and Yankee teams he played for in his defensive prime.
Nettles only had three seasons with an OPS over .800 and those were his age 31-33 seasons with the Yankees. He hit a career high 37 homers in 1977 and hit 32 homers in 1976, the only two times he ever hit more than 30 home runs. He actually finished with a fairly high total of 390 home runs in his career. Nettles actually enjoyed a decent walk rate, but his low batting averages kept his career OBP around .329. Then again, OBP was not considered as important back in the 70's and 80's. That's also an acceptable mark due to also hitting for some power.
By any standards, though, Nettles has fringe Hall-of-Fame credentials with the merits of his glove alone. However, as defensive statistics are not always agreed upon, having about 20 of his career WAR associated with his defense alone sort of hurts his case. It's possible the Veterans Committee votes him in one day, but his case isn't as strong as some other third baseman.
After all, Ron Santo was voted in posthumously in 2012 after deserving to be in the Hall forever. Nettles is still a player well worth remembering, though. At one time, Nettles was one of the better defensive third basemen in the history of the game.