Here's the literal evidence I presented with my opinion:
1) Frelick was a college draft pick whose calling card was his elite hit tool. Those are precisely the types of guys who move quickly through the minors as Frelick already has. Next step in the development process: facing MLB pitching.
2) He's slashed .331/.403/.476 in 638 at-bats during his minor league career with one of the highest contact rates in the minors. This is highlighted by his hitting .365/.435/.508 against AAA pitching, including more walks than strikeouts. Again, nothing left for him to prove in the minors.
3) The Brewers are incentivized to have him on the opening day roster next season as they could be eligible for an extra draft pick if he finishes in the top 3 of the rookie of the year vote. Considering the above AAA stats and his 70-grade hit tool, that is certainly a plausible outcome.
Overall, all of this evidence points to him being on the MLB roster by late April at the latest, if not by opening day.
Your evidence??? Keston Hiura? That's not really evidence considering they're different players. Keston Hiura exhibited a growing K rate as he progressed through the minors, which in hindsight, was a huge warning sign as to how his production would translate to the majors. Frelick, on the other hand, struck out a mere 7.4% of the time in AAA, with one of the highest contact rates in all the minors.
Hiura didn't fail because they rushed him through the minors. Hiura failed because he had a huge hole in his swing that was exposed once he faced major league pitching.