I don’t know how accurate this list is, but it is probably a semi accurate depth chart.
http://www.espn.com/nba/depth
No one is saying Mitchell is guarding Lebron, Kawhi, or George, but he could guard (or give you minutes on) most of the 2s and half of the 3s on that depth chart. I’m sure Mitchell could give you minutes on Hunter, Joe Harris, Jalen Green, Barrett, Hayward, Bojan, Okiro, Bey, Wiggins, Warren, Ingles, Ross, Powell, McDermott, Danny Green, Trent, Bogie, Buddy (if you trade him) etc.
Teams start guys at 3 that are similar to the guys I list above much more regularly than starting Kawhi, Lebron, or Luka at 3. Those guys are 4s most of the time. Those 3s I list above might be “big” but they aren’t going to take you on the post and bully you. They want to shoot and slash. Mitchell can get into their bodies and make life hard.
Ironically, people here wanted Bouknight because he could play 3. Mitchell ate his lunch. Modern 3s aren’t Scottie Pippen and Lebron. Those are 4s. Modern 3s are guys who would have profiled as 2/3 just a few years back.