MIAMI — The day before Boston’s Game 7 triumph over the Philadelphia 76ers, Celtics point guard Rajon Rondo was asked about Doc Rivers’ adage that suggests that, as goes Rondo, so go the Celtics.”Oh, man, that’s a lot of pressure,” Rondo deadpanned. “I’ve heard it before. I don’t know if it’s true.”It is true. When Rondo is engaged, he has the ability to change the complexion of a game. Just ask the 76ers after Rondo kicked it into takeover mode in the final four minutes of Saturday’s Game 7 in Boston and pushed his team through to the Eastern Conference finals.Nathaniel S. Butler/NBAE/Getty ImagesRajon Rondo couldn’t get it going for long against the Heat in Game 1.The Celtics desperately needed that Rondo on the floor Monday night against Miami. As much as Rondo loves to stress that the Celtics are not a “one- or two-man show,” they were facing a team with a vaunted one-two punch in LeBron James and Dwyane Wade.The Celtics clearly required big efforts from Rondo and Kevin Garnett.Instead, Rondo labored through much of Monday’s 93-79 loss to the Heat at AmericanAirlines Arena. Yes, he flirted with another triple-double by posting 16 points, nine rebounds and seven assists over 44:20. But Rondo misfired on 12 shots, turned the ball over four times in the first quarter and never was able to consistently get his teammates involved.Here’s all you need to know: In Boston’s 35-point second-quarter outburst, Rondo shot 4-of-7 for eight points with three assists and zero turnovers.In the other three frames, Rondo was 4-of-13 for eight points with four assists and four turnovers.As goes Rondo, so go the Celtics.”He’s got to be in attack,” Rivers said. “I thought the second quarter he was attacking and attacking. I thought he was reading a lot instead of playing on instincts. I think sometimes his IQ hurts him at times. He’s trying to read the defense, but you can’t read and play with speed at the same time.”We go through it a lot — at least Rondo and I — about, ‘Rondo, just trust your instincts. Your speed has to be part of it. Your instincts will take over. You’ll make the right decision.’”Rivers conceded that Rondo’s teammates need to make shots, noting how the Heat gave space to wings Ray Allen and Mickael Pietrus — a combined 1-for-8 for seven points — then clogged the paint to detour Rondo from driving.For his part, Rondo said the Celtics simply dumbed things down in the second quarter, taking some of the thinking out of the game.”We called maybe two or three sets, kept it simple and got good looks,” he said.Asked why, then, the Celtics struggled so much in the second half, Rondo offered, “We’re human.”Yes, but we’re not quite used to Rondo being human. He’s Mr. Triple-Double. He has nine career postseason triple-doubles — second-most among active players and tied for the fourth-most all time. All nine of Rondo’s triple-doubles have come in the past four postseasons and are more than all other NBA players combined over that span (seven), according to ESPN Stats & Info.Rondo had recorded at least 11 assists in nine of his previous 12 games this postseason. What’s more, he had dominated the Heat during the regular season, averaging 18.7 points, 13.7 assists and 7.7 rebounds in three games.Rondo was potentially Boston’s biggest mismatch. Its X factor. But Monday he went quiet and, maybe not surprisingly, so did Boston’s offense.Asked what Miami did to make his life difficult, Rondo said, “They put different guys on me. They shrunk the floor. Other than that, I don’t think they affected the way we play, it’s just a matter of making shots and getting stops.”Which is a fancy way of saying what Rivers often repeats: It’s a make/miss league. But for a Boston team where offense rarely comes easy, Rondo couldn’t find a way — outside of the second quarter — to consistently put points on the board.As the quarterback of the team, that falls on him. Yes, Rondo’s teammates didn’t help him out by making shots — Celtics starters not named Garnett were 10-of-36 shooting (27.8 percent) as Paul Pierce, Allen and Brandon Bass combined for a mere 26 points.But Rondo seemed off from the start, committing four first-quarter turnovers, including a particularly lazy giveaway to LeBron that led to an easy dunk and had the Heat up by double digits early.He eliminated the turnovers after the first frame — not giving the ball away again — but in the third quarter he missed five of six shots, got tagged with two personal fouls and a technical for shoving Shane Battier, and did not register an assist.That’s not acceptable. Not in this series, when the Celtics clearly need to lean on him.Let’s make one thing clear: Rondo is not to blame for the loss and the bar might be set unreasonably high based on his recent exploits, but the Celtics need more from him.As goes Rondo … well, you know the rest.Rondo took a diplomatic approach to Monday’s loss.”They did what they were supposed to do,” he said. “They won Game 1. They can’t win the series in one game, so we’ve got to get ready and focus on Game 2.”No one more than Rondo.