Name 15 starting short stops that are worse fielders than Bogey.
Now, if you want to claim the 11-20th best SSs are "average", you might have an argument by claiming Bogey is number 20, but to me, even that is a stretch, wishful thinking or homerism.
Personally, I'd rank him around 23rd to 27th, based on the numbers. None of us have watched every SS play by every MLB SS.
Devers still has upside. I get that. He's very young and has raw talent.
I do think he can develop into a plus defensive 3Bman. My problem is concerning the time frame. We're in a 2-3 year window of having a superior chance at winning a ring. It's not an ideal time for "on-the-job-training." That's my biggest concern- not whether someday he may or may not become a plus defender or even average.
I'm 100% positive Moose would be significantly better on defense than Devers in 2018 and most probably 2019 as well. That may not be reason enough to sign Moose over a 1Bman, but it is certainly something that should be factored in when making that choice.