Spurs: 3 Ways Lonnie Walker must develop to reach next level

Spurs: Lonnie Walker's team defense fundamentals need some work
While Lonnie Walker was never exactly known for his defense, he's actually had some impressive showings this past season when defending the ball-handler. Keeping that in mind, by the All-Star break, factoring in all players in the NBA that had played at least 500 minutes, Lonnie Walker sat at 18th in the league in the toughest defensive matchups, according to BBall Index.
Not only that, but according to these same stats, no other Spurs player had more difficult matchups up to that point, even including good defenders like Dejounte Murray and Derrick White. In this way, even considering his not-so-good defensive stats, Lonnie deserves some credit for taking on some difficult players.
While he had many instances of great on-ball defense though, his off-ball defense was pretty uninspiring on many occasions. Lonnie still has some trouble fighting through screens, is prone to over- and under-helping, and sometimes ball-watches and loses track of his man.
Many of Lonnie's defensive metrics are very below-average to the point that some stats make him out to be one of the worst defenders in the league. To me, these stats come as a result of the previously-mentioned tough matchups that he faced throughout the season in combination with his lackluster off-ball defense. In reality, I think he's at least a slightly better defender than those metrics indicate.
Thankfully, off-ball defensive fundamentals are not particularly difficult to teach and can be learned by practicing and watching film: something that Lonnie has alluded to doing this offseason a few times throughout the season. Lonnie could significantly benefit from studying other well-known defensive-minded players in the league like Draymond Green, Jimmy Butler, and Jrue Holiday, and even some younger players like Lonzo Ball and Matisse Thybulle.