I'm not saying you're wrong about Davies as a player but I think Silva's decision to give him the captaincy also suggests that he may agree with what I've been saying on here for years - that captaincy is a fairly redundant role in the modern game and is more given as a little perk to the individual rather than with a belief that it will have a material impact on the performance of the team.
I think that may be because there are so few real leaders. I think that any team that has a player that is a genuine leader of men will benefit hugely from them.... that is not to say that Tom Davies is or ever will be such a player.
If you look at players like Keane, Gerrard, Adams to mention just a few they certainly helped make the team greater than the sum of the parts... unfortunately, a rare breed and hard to find.