According to Synergy stats, LeBron spent significant time guarding two guys in the series, Leonard and Parker (2=made 2, 3=made 3, +1=and1, X=miss, T=turnover, F=foul):
Guarding Leonard:
G1: 2,X,T (2 points, 1 turnover, 3 plays)
G2: 2,F,F (2 points, 2 fouls, 3 plays)
G3: 3,T,2,T,3,3,2+1 (14 points, 2 turnovers, 7 plays)
G4: 2,F,X,2,3,X,2,2 (9 points, 1 foul, 8 plays)
G5: 2,X (2 points, 1 play)
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Overall: 29 points, 3 fouls, 3 turnovers, 22 plays
Guarding Parker:
G1: no plays
G2: no plays
G3: F,F (0 points, 2 fouls, 2 plays)
G4: X,2 (2 points, 2 plays)
G5: 2,2,X,X,X,X (4 points, 6 plays)
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Overall: 6 points, 2 fouls, 0 turnovers, 10 plays
He guarded Leonard terribly in games 3 and 4.
Leonard did a great job of guarding Lebron on iso plays which is why the Spurs didn't need to double and help take Heat initial plays away
Kawhi Leonard On Lebron (NBA finals Series):
Isolation: X,F,F,2,X,T,X,F,X,2 (4 points, 3 fouls, 1 turnover, 10 plays)
P&R Ball Handler: 3,F,3,T,2,T,3,3,X,T,2,X,X,X,X,X,3 (19 points, 1 foul, 3 turnovers, 17 plays)
Post-Up: T,2,2,2,F,F (6 points, 2 fouls, 1 turnover, 6 plays)
P&R Man: 2,2,2 (6 points, 3 plays)
Spot-Up: X,2,X,3,F (5 points, 1 foul, 5 plays)
Off Screen: N/A
Hand Off: T (0 points, 1 turnover, 1 play)
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40 points, 7 fouls, 6 turnovers, 42 plays
though Leonard was terrific guarding LeBron on isos.