Finals MVP in 1999
Finals MVP in 2003
Finals MVP in 2005
Not Finals MVP in 2007 because Tony Parker feasted on Boobie Gibson, but still clearly the best all-around player on the team. 1st-team All-NBA and 1st-team All-Defensive, TP didn't even make all-NBA on any team that year and never had (until sneaking onto the 3rd team in 2009).
Would have been Finals MVP in 2013 if Lebron and Ray don't hit those shots.
Duncan/Kawhi/TP/Ginobli were all pretty much equally destructive in 2014. If the Heat were a big three and could all be considered stars, then the Spurs were a big 4, because all four of them played a hell of a lot better than Wade and Bosh did.
Duncan was arguably the best player on the court for the Spurs even in the 2015 playoffs. Averaged 18-11-3 with 1.3 steals and 1.4 blocks on 59% shooting, with a 27-11-2 on 11-16 shooting in Game 7. 2nd in scoring and nearly as many assists as Parker while leading the team in rebounds, steals, and blocks. Some "role player".
Duncan was never a role player on a championship team ala Kobe 2000. He was either the sole superstar and clear focus of the entire team (1998-2004), the best player by far among several good players (2005-2009), or one of several relatively equal co-stars (2010-2015). 2015 was his lowest-producing year as a pro, and he still was putting in 17-11-4 and 2.5 blocks/game per 36 minutes, on 51% shooting, and making 3rd-team All-NBA and 2nd-team All-Defensive.