What does "子曰、可與言、而不與之言、失人" mean?

In his book "Confucius Analects, with Selections from Traditional Commentaries," Edward Slingerland translates Passage 8 from Book 15 (15.8) as follows:

The Master said, "If someone is open to what you have to say, but you do not speak to them, this is letting the person go to waste; if, however, someone is not open to what you have to say, but you speak to them anyway, this is letting your words to go to waste. The wise person does not let people go to waste, but he also does not waste his words.

I purchased Mr. Slingerland's book mainly for the commentary because there are many translations of the Confucius Analects on the Internet, but I was still hoping for more precise translations of the words of Confucius, which often seem to be a play on words. Unfortunately, Mr. Slingerland prefers to paraphrase the words of Confucius, as he did with the above passage. Here is my more literal translation of Passage 15.8 of the "Analects of Confucius":

可(가)與(여)言(언), 而(이)不(불)與(여)之(지)言(언), 失(실)人(인), 不(불)可(가)與(여)言(언), 而(이)與(여)之(지)言(언)失(실)言(언), 知(지)者(자)不(불)失(실)人(인), 亦(역)不(불)失(실)言(언). 

[If] permitted (可) to give (與) an opinion (言), but (而) [you] do not (不) give (與) him (之) an opinion (言), [you] lose (失) the person (人). [If] not permitted  (不可) to give (與) an opinion (言), but (而) [you] give (與) him (之) an opinion (言), [you] lose (失) the opinion(言). A wise man (知者) does not (不) lose (失) the person (人) nor (亦) lose (失) the opinion (言).

Besides meaning "to be possible," 可 (가) can also mean "to be permitted." Besides meaning "with" or "together," 與 (여) can also mean "to give." And besides meaning "words" or "to speak," 言 (언) can also mean "opinion." But what does 失人 (실인) and 失言 (실언) really mean?

Confucius was so popular and respected because he was a clever person, and a clever person in ancient China knew how to play on words. I suspect 失人 (실인) and 失言 (失言) meant more than just "lose the person" and "lose the words," respectively, which are the common translations for the two expressions. For example, the word 失意 (실의) means "to be disappointed," but it literally means "to lose (失) meaning (意)," so if the 失 in the above passage were translated with the meaning of the word 失意, then 失人 (실인) would translate as "disappoint (失) the person (人)," and 失言 (실언) would translate as "to lose the meaning of (失) the words (言)."

If someone asks for your opinion, but you do not give him one, you do not "lose the person"; you "disappoint the person." If someone does not ask for your opinion, but you give him one, anyway, you do not "lose the words," you lose "the meaning of the words" or rather "the effect of the words."

Besides meaning "to lose," 失 (실) can also mean "to hurt," "to offend," or "to spoil," so 失人 (실인) could also be translated as "to offend (失) the person (人)," and 失言 (실언) could also be translated as "to spoil (失) the words (言)" or "to spoil (失) the opinion (言)."

Finally, besides meaning "to lose," "to offend," and "to spoil," 失 (실) can also mean "to mistake," so, the Korean word 실언 (失言) literally means "to mistake (失) the words (言)," but translates as "misstatement" or "improper remark."

The meaning of the passage: "A wise man knows when to speak and when not to speak."