Roddick leads Sampras in hold% on EVERY SINGLE SURFACE.
Unless we assume that Roddick is the better overall player who holds more often despite having a worse serve, Roddick is easily the better server.
Since Sampras leads Roddick in break% by a healthy margin on every surface, we can safely conclude Sampras has the better ground game.
Ergo.
Roddick is easily the better server than Sampras.
It's not close.
The only reason to think Sampras is a better server is "erhmagherdd eye test" and being mouthbreathing idiot
That depends on what you are looking at :
Slam QF and above on non-clay surfaces(since Roddick didn't even make a QF at RG):
Sampras' hold % is 91.1%
Roddick's hold % is 86.2%
A significant ~5% difference
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Also ,
No of matches for Roddick vs top 10 = 110/828 = 13.29%
No of matches for Roddick vs top 20 = 191/828 = 23.01%
No of matches for Sampras vs top 10 = 197/996 = 19.78%
No of matches for Sampras vs top 10 = 341/996 = 34.23%
Roddick playing a clearly lesser% of top 10/top 20 players counterbalances Sampras having a clearly better ground game (atleast to a great extent)..
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also to be highlighted is :
Hold % vs top 10 ...Sampras ...87.7%
Roddick ....81.6%
A significant 6% difference
Hold% vs top 20 ....Sampras 87.8%
Roddick ....85%
Difference reduces here by quite a bit.
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If it is a high stakes match or vs a top player (top 10 or known rival), I'd give Sampras the edge.
on a more "normal" match, I'd give Roddick the edge.
But nice effort at categorizing all those who call Sampras' serve better as idiots without even looking at the context or stats in detail properly.