Handpicking two games as signs of great improvement doesn't really work (and I wouldn't really call the Hawaii in 2017 a close game).
There were signs of improvement last year but Zach Wilson's best wins are Hawaii and Western Michigan (and I believe BYU has nine opponents this year better than either of those teams).
The BYU offense averaged 16 ppg against N Illinois, Boise State, and Utah. For comparison, the oft criticized Tanner Mangum averaged 19 ppg against Arizona, Cal, Wisconsin, Washington, and Utah State.
I'm hoping that things are improving but I wouldn't dare book tickets to the Hawaii Bowl yet.