During the process of voire dire I believe the lawyers would have been very favorable towards juror #8 because he possesses qualities which enables him to be sympathetic to the boy, we can see this in the remarks he makes early in the movie by the way he sticks up for the boy because of is background with his mother having died at an early age and his father having spent time in jail as well as being abusive.
What the Lawyers have to look at are the more abstract characteristics that juror#8 has that makes him seem to go on the favor of the boy than just the overly trivial theory that someone similar to your client would be a good juror in the case.
Jurors # 8 profession could have been a hard one to read for the lawyers though, on the prosecutions side they could make the mistake by relying on the stereotype that because juror #8 is an Architect and is at a higher station of life than the common man being selected that he would be less likely to be sympathetic to a boy of Hispanic ethnicity from the slums, not following one of the key rules in the voire dire process the relatively few stereotypes will hold up to be true.
Juror Profile.
Once the lawyer has examined all of the aspects and issues that will arise at trial, he should then determine which variables would play for or against his client. This will be a lengthy process because so many variables need to be considered. Among these are: race, age, sex, marital status, family history, occupation, religious affiliation and financial status. This is a small sample of the hundreds of variables that could be considered. Every possible avenue does not need to be explored; only those that the lawyers believe will be relevant in the determination of the case.