Best Defensive Players in the System

I assume you mean minor league system, not the Sox OF, but including guys like Lin, Marco and Quiroz?

This has never been a thing. The Red Sox may release their defensive minor league players of the year, but that's about it. It would be next to impossible to do it without a team of scouts watching every minor league game.

Defensive stats are pretty unreliable in the minors especially.  So you have to hope that the games that a scout is watching are typical defensive games for each player.  And they need to also have the opportunity to make difficult plays.  I don't think you can get a good read on a player's defense without watching a lot of games.

To jimed’s point, even major league defensive metrics still leave much to be desired. For example, UZR seems like an old stat, but when new, not long ago, it was used to wrongly paint Ellsbury as a well below average defender because of routes in CF and arm. There are no easily tabulated slash lines on D. And I have been told that some advanced metrics paint Nunez as an above average defender, as the final out in ALDS clearly showed. Sarcasm.
Defense is so difficult to quantify, yes?

We do know about Lin, and Dalbec’s soft hands (and power) may make him a good 1B some day, assuming Dever’s D continues to mature. As an aside, stories and pictures of young Jarren Duran (though my memories may be playing tricks) remind me a lot of my childhood hero Jimmy Piersall. That would be a good thing.

Now that you bring them up, is it possible that Chavis could ever learn to play 2B? Any position? Would he actually be a bad defender at 1B? Now that the Sox have become a strong defensive team, they should make every effort to remain so. I was hoping that Dalbec and Devers would mature into the strong D/ high OPS 1B/3B of the future. Casas may be even better? Wow. So many good options coming up.