Yes, these tiers deserve some comment.
In tier 1, you have listed three players Gonzales, Rosewall, Laver, plus others like Newcombe, Emerson, Sedgman all of whom rated Hoad number one all-time.
I don't think that Hoad belongs in a "tier", he is more in a category of his own, the strongest player, but also the most range of strokes of any player.
Also, you have named 29 players. How about cutting it down a bit, to about 12? Like this:
These first four rankings are Rosewall's own choice in 2010.
Plus the following, my own choices:
Sedgman (when engaging his "extra gear")
Tough to judge Richard Williams in 1914 to 1916, or even Lacoste and Cochet.
Below this, you could give honourable mention to Emerson, Newcombe, Trabert, Ashe, Nastase, Smith, Connors, McEnroe, Becker, Rafter, Edberg, Perry, Crawford, etc.