Re: Simona Halep (România)
To be honest, doubles these days is more or less
a) a fun thing to do for your casual ATP/WTA player pairing up with a friend
b) a way to gain some money
c) a resort for tennis players whose footwork or fitness suck too much for a singles career, but still can compete for slams and stuff as doubles specialists
The best players in singles usually don't play doubles to save energy.