I already mentioned the .21 this year. Even the .21 would be second-worst in all the majors right now of qualified players. So even ignoring what he's done in the past, his rate is still almost twice as low as guys like Dunn, Reynolds, Howard, etc.
Your point was his lower strikeout totals compensate for the lack of walks somewhat. But since BB-K ratio uses only those two numbers, this suggests that's not the case at all. In fact, he's faring even worse when looking at these two numbers in isolation.
The strikeouts are still on the high side. They're not problematic, but short of improving his walk rate, the guy will definitely have to continue to cut down on them even more if he wants to be successful. If he does either (or both), no doubt about it - he will be one of arguably the best sluggers in the game. But he does definitely need to do at least one or the other.