What are the criteria for judging the closeness of a y DNA match?

[firemonkey]

I have several Dutton yDNA matches with an earliest known paternal ancestor Zachariah Dutton. 1 at 67 markers and 7 at 25 markers. Of those 8, 6 have tested to 67 markers and 2 to 700 markers. I also have a couple of other surname matches that may connect to Zachariah. Purely by chance I have a small autosomal match, at Ancestry, that has Zachariah as an ancestor.

There is a Facebook group re Zachariah Dutton https://www.facebook.com/groups/zachariahduttonfamily. Autosomally I connect to Duttons from Pennsylvania, who were Quakers.