He can hit wide open
jumpers... which he isn't getting without Westbrook on the court.
The problem with posting these days, is you have to be a good passer as well, because it's easy to double. So, Ibaka could develop a high % post move, but if he actually used it effectively, he would get doubled, and would have to rely on his passing skills. It's the same problem Dwight had posting for the Lakers this season. He can score at a high % from the post, but he isn't a great passer, and is easily forced into turnovers when doubled. The Magic surrounded Dwight with 4 shooters, making it so he didn't have to pass as much from the post, and had more room to operate.
Pounding the post on offense for an extended period of time doesn't exist in the NBA anymore. It's simply not an efficient way to score with the current rules. You're better off just ISOing on the perimeter, and jumping into defenders to get FT's.