His
tracking numbers are flat out awful, on average players are shooting close to 12% better than league average when Neto defends them, so if he gets switched onto someone and they attack him good luck stopping him without help defense. I'm not a big fan of
DRPM for the Jazz since I think Gobert heavily influences the results, but he has the worst of all 3 of the Jazz guards at -0.66. Exum is a -0.42 for comparison. According to
bball reference's On/Off stats while in his limited minutes the Jazz have a much higher ORTG, their DRTG has a slight down tick when Neto is on the floor. Also while Neto does have a lot of lineups with frankly insane DRTGs, his
top 3 most played lineups according to NBA.com all have higher DRTGs than what the Jazz on average have.
When you watch him play defense he's pretty similar to Korver in that he's a smart defender who knows where he should be and what he needs to do most of the time, and for the regular season against most teams in the NBA he will be fine. But if he gets ISO'd against any of the many talented PGs not just in the West but in the NBA in general he simply can't guard them due to his size limitations, but also his average at best lateral movement (Rubio struggles with this too while Exum is very good moving laterally), and smarts only get him so far, and the same happens with Korver in the playoffs which is why the Cavs would only play him for 20 - 25 mins a night in the playoffs.
CP3 makes it work because he's one of the best PGs in the NBA at stripping the player of the ball, and he's also very good at contesting 3pt shots without fouling which isn't something I would say for Neto.
CP3's tracking numbers aren't all that impressive either but you can clearly see he's at least serviceable if he gets attacked off a switch while Neto gets completely abused in comparison.
If you want to argue that Neto is an average defender I wouldn't necessarily disagree, but he's not a good defender and he's not a guy who can successfully play within a switching defense. I think he's a below average defender who is good at team defense but if he gets targeted you're going to have to pull him off the floor, which I wouldn't say about Exum and to a lesser degree Rubio.