Pat Riley, coach of the NBA champion Miami Heat, announced yesterday that he would take an indefinite leave of absence from the team. Riley is stepping down to have knee and hip surgery that will require at least a month of recovery time. The coach had in recent weeks walked with a noticeable limp, but hoped to postpone surgery until after the season.

“I’m just tired of the pain and medication,” the 61-year-old coach said. He will have knee surgery on Friday and then prepare for surgery later on his hip. (The Lakers’ coach, Phil Jackson, underwent hip surgery during training camp and was away from the bench for about a month.) “My plans are to return,” Riley added. “When that will be, I can’t tell you.”

Apart from contributing to a day of coaching tumult in South Florida, where Dolphins head coach Nick Saban decamped after a 6–10 season to return to the collegiate ranks, the news adds to a dramatic season for the champs. Center Shaquille O’Neal and guard Dwyane Wade — the duo that accounted for 47% of the Heat offense last season — have been out with injuries. O’Neal injured his knee in the early going, has been out since mid-November, and isn’t expected back until later this month, at the earliest. Wade sprained his right wrist last Wednesday against Chicago and isn’t expected to return until this weekend.

The veteran group of players Riley assembled to support his superstars have shown their age this year, with forward Antoine Walker and guards Gary Payton and Jason Williams, in particular, suffering steep declines in production. Both Walker and forward James Posey were deactivated for last night’s game against the Clippers because of missed conditioning goals.

Riley, a veteran coach with five championship rings, pulled together this ensemble as team president, before taking over as coach last season 21 games into the campaign. Many regarded his effort in guiding the Heat to the title as his finest hour; he changed offensive and defensive strategies during the finals to stop a surging Dallas team and guide Miami to victory.

The Heat have struggled without their superstars, how will they fare without their coach?

After O’Neal’s injury, many — myself included — ticketed the Heat for the lottery, but thanks to stellar play by Wade and reserve center Alonzo Mourning, the Heat hung tough and went .500 without their big man; on Christmas Day, they thrashed the Lakers 101–85. But in the aftermath of Wade’s injury, the bottom has fallen out. The Heat have lost three in a row, including a 97–68 pummeling by Orlando on Saturday, the team’s sixth loss by more than 20 points. As expected, the team has struggled offensively and their defense has begun to spring leaks.

Conspiracy theorists and Riley haters alike will undoubtedly pin the timing of Riley’s departure to dire news about Wade’s return. That party line will say this signals throwing in the towel on this season and, if Wade is out for any extended period — 10 days does seem like an optimistic projection for a wrist sprain — then the Heat truly are finished and it’s time to start thinking about the draft and next year. The haters will also note that during Wade’s rookie year the Heat were a young, emerging team, while these days, save for Wade and power forward Udonis Haslem, they are an old bunch whose window of contention may have closed right after the victory parade last June.

If that were the case, then I think Riley would simply quit. The Heat have shown surprising resilience without Shaq, and Wade and has healed quickly from past injuries. Also, two youngsters at the end of the Miami bench, swingmen Dorell Wright and Jason Kapono, have emerged as key players contributing major minutes and combining for 27 points per contest in the last five games. In the Eastern Conference, the Heat should be able to stay within hailing distance of the playoffs until Shaq returns.

What sort of team O’Neal finds upon his return is less clear. Although Riley said he will “stay in close connection with the team,” during his absence, he’s giving up the reins to a man with some tendencies and coaching experience different from his own. Rothstein was the Heat’s first coach when the team joined the league in 1989. He coached them for three seasons, then coached the Pistons (where he had the unenviable position of replacing Chuck Daly) for a season that coincided with Isiah Thomas’s final year as a player. In Miami, Rothstein liked to run; his Heat teams finished in the upper echelon in possessions per game, and with Miami he finds a team in need of an uptempo charge. A lineup keyed by Wade, Haslem, Kapono, Wright, and one of the big men might be Miami’s most effective unit. Yes, I’m including Wade in this unit, but that may be making official what is already true. He’s averaging 7.8 dimes per game, more than the notional point guards, Williams (4.5) and Payton (2.3) combined.

As long as Wade returns promptly, it’s far too early to count the Heat out of the East. If Rothstein can continue to nurture the development of Wright and Kapono, then the Heat will have a solid lineup when O’Neal returns and could be a dangerous team entering the stretch run. At which point the drama could heighten again as Riley returns.

mjohnson@nysun.com