To me, he's just too risky in a top-5. Defense and discipline are two huge factors Yakemchuk needs to work on. There is potential in him b/c the article cites he may not be done growing b/c his older brothers also grew late. Once Yakemchuk stops growing, then he might be able to improve his skating technique. The wait might be longer on Yakemchuk to be a polished product.
Anaheim already possesses several offensive d-men in Minty, Zell, Luneau, and, to an extent, LaCombe. We're missing defense in the top-4. No defensive-D is popping off in the Ducks system right now. The Ducks can expedite that with a top-5 pick.
There are other options at defense before Yakemchuk in the top-5. RD Lev and LD Dickinson look good defensively, we'll have to have a LD play RD if we draft Dickinson.