What point is Holden making when he talks about Stradlater and the "commas" and Ackley's description of the basketball player?
The point that Holden is making here is that people like his room-mate Stradlater and Ackley are unable, or unwilling, to appreciate other people’s talents. This issue first comes up when Stradlater asks Holden to write his English composition for him as Holden is good at English. However, Stradlater implies that the only reason Holden is good at English is because he has a sound grasp of grammar – that he knows where to put commas, and so on. Holden is extremely annoyed that Stradlater doesn’t seem to recognize that there is far more to writing a good composition than just attending to punctuation.
Robert Ackley shows a similar inability to appreciate another boy’s sporting abilities. Holden recalls how he and Ackley once watched a basketball game featuring an outstanding player named Howie Coyle. However, instead of praising him, all Ackley says is that Coyle ‘has the perfect build for basketball’, as if his physique alone accounts for his prowess. This also vexes Holden: ‘God, how I hate that stuff,’ he remarks. Holden thinks that Ackley and Stradlater are mean-spirited towards others and he is disgusted with their attitude. Holden appears to feel this way about many people, not realizing that his own attitude to others often leaves something to be desired.
When Stradlater asks Holden to write his composition, he tells Holden not to make it "too good" by sticking all the commas in the correct places. Holden then mentions that Stradlater's comment about the commas upsets him. Holden hates it when people like Stradlater think that the only way others achieve success at writing compositions is when they put all the commas in the correct places. Stradlater's comment reminds Holden of how Ackley viewed an excellent basketball player named Howie Coyle. Howie Coyle could make a shot anywhere on the court, but all Ackley would say about Coyle is that he had the perfect build for a basketball player. Both Stradlater and Ackley's comments represent the attention they give to outward appearances rather than substance. Commas and Howie Coyle's build are essentially insignificant to their respective fields. Commas have little to do with the substance of a composition, and Howie Coyle is still a successful basketball player regardless of his build. Holden is once again commenting on their "phoniness." Stradlater also indirectly belittles Holden's ability as a writer and Ackley refuses to give Howie Coyle credit for being an outstanding basketball player. In Holden's opinion, both Stradlater and Ackley focus on superficial, insignificant aspects in various situations and refuse to give people the credit they deserve.