He certainly will never have recovery speed like guys like Chabot or Sanderson. No argument there. Personally, I don't see the "so many questionable pinches/plays in deep" that you do. Occasionally, sure, but I've found his decisions on when to jump in and when to stay back to be pretty well calculated throughout the playoffs. It's definitely something he's improved on since last year, which is what you want to see from of a developing prospect.
I would characterize myself as a Yakemchuk skeptic who's starting to appreciate him more, and that has only come through watching him consistently - approaching ten games straight - rather than sporadically. Because there are things about him that have always turned me off. I see the rough skating, the questionable athleticism, the upright posture that reads as lazy. And when I'd tune in for a one-off period in January, that's all I could see. Watching him every night, though, those things have started to bother me less. I'm still conscious of them, and take them into account when projecting him as a player, but I can also see beyond them to the positives in his game.
Put another way, instead of being annoyed by him not being who I want him to be (e.g. a big, smooth, creative offensive star), I'm starting to appreciate him for who he is and what he could become. I don't see him becoming a star offensive defenceman, but I can see the makings of a good (or maybe even great, depending on how well he defends) top 4, 30-40 point two-way RHD.