(Ronald Martinez/Getty Images)

Serge Ibaka is expected to miss the rest of the playoffs because of a left calf injury suffered in Game 6 of Oklahoma City’s second-round series against the Los Angeles Clippers. It’s a big loss as Oklahoma City prepares to take on the San Antonio Spurs in the Western Conference finals: Ibaka was the Thunder’s third-best player this postseason in terms of win shares (1.5) behind Kevin Durant (2.2) and Russell Westbrook (2.0), and also averaged 15.1 points, 8.8 rebounds and 2.7 blocks (second best in the league) during the regular season. In the playoffs, his 12.2 points per game were produced all over the court.

Serge Ibaka 2014 NBA Playoffs shot chart

The 6-foot-10, 220-pound big man did a great job guarding the Spurs’ Tim Duncan during the regular season and gives the Thunder a defender who can help guard out to the three-point line, often taking away a great look from beyond the arc and replacing it with much less desirable one. As a result, San Antonio had an effective field goal percentage — which gives extra weight to three-point shots — of just 46.4 percent against the Thunder when Ibaka was on the court during the regular season. That ballooned to 60.4 percent with Ibaka on the bench. Spurs also saw a dramatic reduction in second-chance points (16.3 per 48 minutes with Ibaka on, 9.4 off) and points scored by the Thunder off the fast break (20.1 per 48 minutes with Ibaka on the court, 4.3 off) in addition to points scored off turnovers (20.8 per 48 minutes with Ibaka on, 17.3 off).

“It’s unfortunate that Serge’s injury took place,” Thunder Coach Scott Brooks said. “He spends so much time preparing for these moments all season long. [It’s] definitely a setback for us. He does a lot for our team. But we have a mentality here: next man up.”

That “next man up” is either Steven Adams or Nick Collision.

The 7-foot Adams is grabbing 3.6 rebounds and blocking 1.4 shots per game while playing 16.3 minutes a night. The downside? He is also picking up almost three personal fouls (2.8) in that same time period. He can’t be a viable replacement option if he isn’t on the court.

Collision hasn’t provided much offense. The Thunder is averaging 98 points per 100 possessions this postseason when he is on the court and 112.5 when he is on the bench — not exactly what you want to see in a potential replacement. Oklahoma City also has a 41.5 percent effective shooting percentage with him on the court, but 52.5 percent when he isn’t.

Perhaps the biggest beneficiary of the Ibaka injury will be Tony Parker. Without Ibaka, the Thunder lose a consistent source of rim protection and it will allow Parker to get into the lane and collapse the opposing defense. Parker currently leads all players this postseason in team points per game off drives with 10.4 (minimum 10 games played).

“The timing of [Ibaka injury] is unfortunate,” Thunder General Manager Sam Presti told reporters in a conference call.