Popovich is a good coach but people are putting him on a pedestal that is way too high.
He started his career as San Antonio coach by pulling an combination Pat Riley and ML Carr move. He fired a very good coach Bob Hill who had won 62 games the previous year(A Pat Riley) but was struggling because he lost David Robinson and Sean Elliot. He then did a better ML Carr in that he tanked and won the lottery.
So the following year he has Duncan, David Robinson and most of the team that Bob Hill coached to 62 victories.
Rick Pitino might have been the "best coach" ever if the Celtics had gotten Duncan. (Although Rick was such a bad GM he might not have done as well and he certainly wouldn't have had such a great supporting cast)
So Popovich has one of the greastest NBA players of all time in Duncan plus a great supporting cast. So he basically becomes a Casey Jones as a coach and lets them play. Note that nobody has ever said that KC Jones was the greatest coach ever but he got to the finals 4 out of the 5 years that he coached the Celtics and won 2 championships and if McHale doesn't blow out his ankle in 87 and If Len Bias didn't die after the draft. Casey Jones might have won many more championships. Nobody has ever called Casey Jones a great coach :)
What Popovich did very well is that he recognized that drafting late in the draft with a great team and a great cornerstone he could take risks on upside or on European players that might or might not come over right away. So he got Parker, Ginobili and Splitter.
So if he didn't tank and get lucky we would not be talking about him being the best ever coach.
If he didn't pull a sleazy firing of Bob Hill we wouldn't be talking about him being the best ever coach