I'm going to say no, based on my experience. I have NVLD, so in kindergarten I had a 12th grade reading level, but couldn't tie my shoes. I never had any meds as a kid except vitamins.
Anyway, for me, trying Ritalin as an adult, turned off my hyper-verbal thought process. But that sorta had the side effect of like, making me dumb. My reaction times driving and whatnot got WORSE because the verbal thought process was turned off. My theory is (I don't have specific data to support this) that it turns off the left brain hemisphere. Or it might just work to turn off/turn down the "overactive" hemisphere. As far as speech in particular, though, I do think you're expecting a bit much.
Giving Ritalin to a child seems asinine to me, though. 10mg as an adult made my pulse go from 70 to like 95-100. 10mg. I was prescribed 20, but 20 made my blood pressure like 150/90, and pulse 100+. And I got no positive effect from it really, except it made me more assertive/impulsive (which is in most ways a bad effect.)
I mean, you can give it a try and see what happens, but keep the dosage low if you do it. Don't let your kid have like 50mg a day or something. I don't have kids, but I'd not let mine touch that stuff, though.