These are not the bad old days when Paul Pierce had to play out of his sneakers to win a game. (Pause while Celtics fans breathe a collective “Amen.”) But after a 97-90 loss to the Nuggets last night, the captain was well aware that 2-for-14 from the floor isn’t going to cut it either. Facing more concerted resistance from a Denver outfit whose coach, George Karl, has been praising Pierce’s emergence in the wake of Rajon Rondo’s injury, Pierce had a devilish six rebounds, six assists and six fouls to go with his 10 points. He was 1-for-8 in the second half and 0-for-3 in the last quarter. And while it was the Celts’ defense and rebounding (Denver had seven offensive boards in the second half) that doomed them mainly, Pierce knows he needs to do more. It was no coincidence that he averaged 17.0 points and 9.4 rebounds while the Celtics were winning eight of nine games entering last night. “It’s not as much as it used to be back in the day. You know, back then . . .” said Pierce, his voice trailing off in a laugh as he recalled those sorry Celtics times. “If I can get between 15 and 18 points, then I like our chances,” he went on. “I have to be consistent. I have to give us between 16, 18, maybe 20 points a night and do things across the board. If I’m doing that and everybody else is playing well, then we give ourselves the best chance, I think.” Pierce went just 2-for-12 from the floor in the last game before the All-Star break, but that was part of an overall hideous night as the C’s beat Chicago, 71-69. He knows he has to push through any shooting woes. “I just know to stick with it,” he said. “I’m never going to get discouraged with the way I’m shooting.