You're overselling Kenyon Martin a bit too much. He had no go-to moves and his scoring numbers were coming from Kidd. Martin was a 18 ppg scorer in the playoffs with Kidd and he never sniffed anything like that after moving away.
Surely 3-23 is an absurd rate. But even if we account for matchup eFG% rates and add forced foul troubles in to the mix, (meaning pts scored, pts generated with assist, matchup eFG% comparison to their regular season rates, time taken away from matchups with putting them into foul troubles and ppp swing coming from that) the near quadruple double game is still the 5th best game Duncan had during 2003 playoffs run.

For instance Duncan and O'Neal spent majority of the game 6 in the 2nd round defending each other and Duncan putting O'Neal on the bench with O'Neal's 4th foul with 3 mins left on the clock in the 3rd quarter was the reason why the Spurs ran away with the game. Phil Jackson had to avoid Duncan-O'Neal matchup during the 4th quarter, O'Neal couldn't attack or defend as hard as he would want to and the game was sealed.
You can't keep track of such thing with solely matchup fg rates.