She's mid tier jg at best right now. She's okay at most things, but great at nothing. Unless she's got a dive buddy or two, her ult is basically a suicide button because she won't blow up anyone on her own with it in teamfights. It's all about setting up a toplane bruiser or fighter or a midlane melee like zed or fizz.
People have been playing ranged poke or zone control comps mostly with disengage as the focus for awhile now. Which SHOULD make hard engage and burst the ideal answer... of which vi would be a great example. So if that's not visibly being used or succeeding in solo queue or pro scene, then it's a sign that maybe hard engage stuff like vi isn't strong enough.
At silver or even gold, it's not so much about what you see as capable of working to determine if it's good or not but rather about WHY it works. Did it work because it's actually good? Or did it work because the other team had one or more people trolling or inting all game? Perhaps even it worked because... there was a person doing unranked to challenger or whatever on one side... so he/she could pull off literally anything at that elo.