Tim Duncan has won five NBA titles, but even he was amazed at how simple Warriors coach Steve Kerr made it look taking a team to a title.

The legendary Spurs star forward sent his former teammate a text saying “It’s that easy, huh?” as congratulations for Golden State’s championship in Kerr’s first year running the team.

Kerr went 83-20 in his rookie coaching season, combining the regular season and playoffs. The Warriors twice fell down 2-1 in the postseason — to the Grizzlies and Cavaliers — but responded with three straight wins on both occasions.

“It’s ironic, but the unexpected thing was that everything went exactly as we hoped,” Kerr told reporters Thursday at the Warriors’ practice facility. “That never happens.”

Kerr was credited with key Game 4 adjustments in both those series to turn them around — having Andrew Bogut cover offensively inept Grizzlies forward Tony Allen in the second round then putting Bogut on the bench in favor of Andre Iguodala in the Finals.

Kerr is planning on putting the X’s and O’s away for now.

“I just want to sit on my couch and watch the US Open and drink beer,” Kerr said.