I decided to go over the 01, 02, 03 Lakers/Spurs playoffs series to see who was primarily guarding Shaq and how effective they were in guarding him. I didn't go over every possession, but I decided to look at every FGA and turnovers forced that Shaq had in those games. I didn't get every game from that 01-03 span because youtube didn't have all of them, but I did get a majority of the games.
vs. Duncan: 21-49 (.429), 8 TOV (5 of them charges/offensive fouls drawn)
vs. Robinson: 31-63 (.492), 5 TOV (1 offensive foul)
vs. Rose: 15-27 (.556), 2 TOV (2 offensive fouls)
vs. Other big men (Bryant, Willis, Walker): 6-12, 1 TOV (1 offensive foul)
vs. Guards: 0-3
vs. open shots with no one guarding Shaq: 11-13
I also kept track of double teams both before the shot and double teams during the shot (sometimes both happened). I didn't count double teams that had no effect on the shot or soft double teams.
vs. Duncan: 11 before shot, 14 after shot, 20 total double teams (35.1% double team%)
vs. Robinson: 10 before shot, 15 after shot, 23 total double teams (33.8% double team%)
vs. Rose: 4 before shot, 5 after shot (33.3% double team%)
vs. other big men: 2 before shot, 3 after shot, 3 total double teams (23.1 double team%)
In 2003, The Spurs made a concerted effort not to double Shaq. They even mentioned it in one of the broadcasts where Popovich told them that they didn't want anyone else to beat them. In the other years, Shaq got a decent amount of double teams and very few triple teams. Most of the double teams I saw were soft and had no effect. Shaq was making his move by the time the double came.
Now here are the stats for who was guarding Shaq in the games Duncan/Robinson played (Robinson missed 1 of the games). This is why I started the project. I wanted to see if Robinson was the sole Shaq defender or if the Spurs took turns defending him.
Duncan 31.0%
Robinson 46.9%
Rose 19.3%
Willis 2.1%
Walker 0.7%
I didn't include any wide open shots or times when guards defended him. Usually, Robinson started off the game vs. Shaq. Then Rose would come in and guard Shaq and take turns with Duncan. Usually in the middle of the game, Duncan and Robinson took turns guarding Shaq even in clutch situations.
Here are Shaq's numbers from 01-03 including regular season and playoffs vs. Spurs.
Per 36 numbers:
vs. Rest of league: 57.4 FG%, .583 TS%, 26.6 PPG, 11.2 Reb, 3.10 AST, 2.71 TOV
vs. With Robinson on Court: 51.7 FG%, .545 TS%, 22.9 PPG, 12.1 Reb, 3.08 AST, 2.75 TOV
Difference: -5.7 FG%, -3.8 TS%, -3.7 PPG, +0.9 Reb, -0.02 AST, +0.04 TOV
Per 36 numbers:
vs. David Robinson: 51.7 FG%, .545 TS%, 22.9 PPG, 12.1 Reb, 3.08 AST, 2.75 TOV
vs. Robinson off the court: 49.5 FG%, .528 TS%, 21.5 PPG, 11.1 Reb, 1.99 AST, 2.68 TOV
Difference: -2.2 FG%, -1.7 TS%, -1.4 PPG, -1.0 Reb, -1.09 AST, -0.07 TOV
Duncan looked slightly better vs. Shaq and the numbers back it up. There were plenty of instances where Shaq couldn't back down Duncan. But Shaq did dunk on him quite a bit. Shaq dunked on everyone from the Spurs.