Wouldn't that just mean he's the worst winger in the competition for doing that then? Surely there are many other speedsters being used in that same context and don't just disrupt, but actually connect with their tackles. It's plausible reasoning to a degree; he wasn't a tackling aficionado on the stats to begin with. But even by Savea's own standards, he's about 17 percent down on his career average.
Since Chris Boyd took over and started doing kick chases...which has worked very well. That supports my point rather than refutes it.
It doesn't mean he's the worst defensive winger in the competition at all. If he doesn't make a tackle but the ball is knocked on, or partially makes a tackle in time for the rest of the defensive line to move up - then he's doing exactly what they want him to do.
I'm not saying it wouldn't be nice for every run up and chase to be a great connecting tackle, but it's a very tough ask.