No, she was always a defense hero. But now defense is lumped together with offense to make DPS. So she was never a support 
This was true of every lesser-used hero. Lower pick rates almost always equals higher win percentage. It has more to do with statistics than hero balance.
Also, Sym is a damage monster if she isn’t very quickly focused down. It’s only her lack of mobility that keeps her from being frequently used at higher ranks and the lack of a lock-on primary is what’s keeping her from being used at lower ranks as much as she used to be.
I don’t he meant her winrate numbers I think he meant in general statistically teams with her had a higher chance
That essentially amounts to win rates, though. The number of teams who have Sym on them are the same as her pick rate and the percentage of win/loss by those teams are mostly her win rate, though it gets a little less precise when partial match credit is factored in.