I wonder how that might play out with the jury. I'm a mathematician, so I'll simplify my thoughts in math speak. Some jurors might think "poor grammar = stupid" and "articulate = smart", but then a different set of jurors might think "poor grammar = my kind of guy" and "articulate = slick, untrustworthy".
In you were the defense, what type of juror would you look for? Also, since this is the first true crime story I have followed, does the prosecution plan their presentation based on the type of jury they believe will be selected? How much time is there between jury selection and the actual trial?
There's a persistent myth out there, that good attorneys can stack a jury with favorable jurors. 'Taint so. Both sides strike jurors they believe are unfavorable. The result is a jury that favors neither party. Scientific studies have shown that after all the procedural steps to assure an unbiased jury, the twelve originally seated were no more biased or prejudiced than the jury that tried the case.
I still have some notes from a course I took in forensic psychology. One of the subjects we studied was jury selection and jury decisions. One major takeaway was that when the evidence is strong, juror personalities, biases, and prejudices don't influence the outcome. Another finding of several studies was that neither experienced trial attorneys nor "scientific" jury consultants were significantly better than random chance at detecting bias and prejudice through the jury selection process.
In civil trials, where the evidence can be more equivocal, some juror characteristics have been shown to have a small effect on the outcome:
1. The hypothesis that jurors who are similar to the defendant will empathize and identify with him has been studied only for one characteristic: race. Although there's some evidence to support the hypothesis, it's not solely determinative of the outcome. There's also evidence that jurors who are similar to the defendant are harsher in their judgment of the defendant. BM, be careful what you wish for.
2. How a juror explains what happens to herself can affect how she decides an equivocal case. For example, jurors who believe what you get in life is the result of your own abilities and efforts (and similarly, that you get what you deserve) tend to "blame the victim." Jurors who see their outcomes as due to forces outside themselves, such as luck or more powerful people, are more likely to sympathize with the victim of misconduct.
3. Authoritarian personalities are generally more likely than other personality types to convict (except when the defendant is an authority figure).
There are juror questionnaires designed to get at these attitudinal factors, and I expect both sides will be using them for whatever advantage they can get, however small.