This was Napoleon sending flowers to the Duke of Wellington, or Ali reciting a positive poem about Frazier. Kevin Garnett, the realist, had to give the Knicks their due yesterday. “The Knicks are the better team,” the Celtics center said of his team’s first-round playoff opponent. “They’ve deserved it. They’ve earned it and rightfully so. I think (Carmelo Anthony) is playing unbelievable, J.R. (Smith), that whole team — they’re playing with a lot of confidence. That’s what you want going into the playoffs.” Garnett’s squad is probably less equipped for the postseason than at any point since he first became a Celtic in the summer of 2007. Beyond Garnett, Paul Pierce, Jason Terry and Brandon Bass, there isn’t another Celtic with extensive playoff experience — not Jeff Green or Courtney Lee, and not even Avery Bradley, though the latter played brilliantly before chronic shoulder trouble knocked him out of last year’s playoffs. As much as the veterans can talk about the difference between regular-season and playoff intensity, words can only go so far — especially in a playoff series against the Knicks. “We really got a taste of it during the season, but when you see how it was during the regular season, you have to elevate it times 10,” said Pierce. “So much is on the line. One mistake could cost you a series. One play could cost you a game. It could all be fatal in a series like this. We have to understand the concentration you have to have. “The things you did during the regular season aren’t going to be the same,” he said. “You don’t have one day to prepare for a team, and now you have three days. Adjustments are being made, and everything is going to be new for you. Guys have to adjust to that. Me, JET, Kevin and the coaches have to get them to understand that.” Rivers, though, knows that the real lessons won’t start until the lights go up at Madison Square Garden this afternoon. “I think you have to learn by fire,” he said. “They can sort of learn by talk and all of that. But veterans always told me going into the playoffs what to do, and I listened, but I don’t think it helped me much. You have to do it. You have to get in it and experience it. And you have to experience it with each individual team you’re with. This is a different team that even JET’s been with. Every year the playoffs are different. And you’re a different team. Guys are playing different roles.” Even so, the veterans have to try and prepare the rest of the roster. The process started long before yesterday.