so looking for 3Bs with at least a couple of 3WAR seasons you get:
Cabrera - who put up 14 WAR as a 3B but only played there for 2 years.
after that:
Moriarity and McManus (way back!), in the more modern era: Kell, Ray Boone, Inge, Fryman.
Boone, Kell and Fryman were All-Stars and obviously Cabrera.
Wert, Bookens and Rodriguez played there for fairly long stretches - so the position was stable, but neither was more than average production player.
So the overall history is maybe average, but it's definitely been since Cabrera's first years here that it's been locked down and that's been a while - too long. Cabrera keeping his weight to 215 and staying at 3b for half a dozen years is still my most disappointed alternate baseball history.