Bobby Witt Jr. has 13 OAA at SS already. He's lapping the league in defensive value contributed, and as such leads the league in fWAR by a fair margin since he's also an elite baserunner and has a 134 wRC+ which he's actually underperforming based on his xwOBA.
Looking at a likely inner circle guy, he's basically infield Mike Trout who just got started a little later.