His arm value over 7 years is -12. It's +1 this year and was +2 last year. I was going off of the last two years. If you think an arm value for a career that is -12 is a good arm, then we probably don't have much to discuss. His fielding run value for his career is -27, his baserunning run value over 7 years is -6, the only positive year being his call up in 2018 at +1. If you think those numbers are average, that's fine, I don't.
I wouldn't assume he's going to end up in Yankee stadium for his career, there are other teams with lots of money and interest.
Edit: Colton Cowser is in the 99th percentile in arm strength, do you consider him to have a good arm or a strong arm? They are not equal things.