A.J. Griffin's intangibles on defense push him over the top
I'm a big fan of looking into a player's advanced stats for clues about their game, and Griffin is no exception. Seeing that he's one of the leaders of his team in true shooting percentage and offensive box plus/minus while having one of the lowest turnover rates on the team tell me that Griffin is an efficient player that makes good decisions, and watching him play only confirms that assessment.
That being said, stats seldom tell the full story of a player, and in Griffin's case, I think his defensive presence and potential go a bit under the radar as a result.
While he isn't the fastest lateral athlete on the planet, he's capable of holding his own on the perimeter against smaller opponents and is quick enough with his hands to disrupt some passes and live dribbles. On the other hand, being that he's already about the same size as Keldon Johnson, he understands how to use that size in the paint to disrupt larger opponents.
In fact, as much as it pains me to say it, Griffin may have already slightly surpassed Johnson in this department. Considering his age, Griffin is one of the stronger wing players I've followed in the past several seasons.
When Griffin is away from the ball, he can move deceivingly quickly for his size, which helps him in emergency/help defense situations, and while it may not always result in a block or steal for him, the quick reaction is usually enough to force a tough shot or a turnover. While he's only averaging about one "stock" per game at this point, the potential for him to make a bigger defensive dent in the stat sheet in the future is certainly there.
Generally speaking, while Griffin's defense may not immediately show up on the stat sheet, there have been enough flashes of his versatility and hustle to warrant a lot of promise on that end of the floor. As his understanding of off-ball defense continues to improve, I think he'll start to look much more impactful on that end in the NBA.