I personally think it's a matter of skill in pre-30's PvP. With my level 16 sniper I was able to one-on-one (and a couple of times two-on-one) every person who was in those matches I played that day. There were three matches in a row where we went against Republic and there was a 29 gunslinger and I was able to beat him on a one-on-one (and this happened multiple times each match). However, he did beat me twice when we went one-on-one but I feel that was more of the levels and not his skill
It's really not "a matter of skill" in pre-30 PVP for a sniper. A sniper will completely dominate that bracket, unless the sniper is terrible / new to MMOs. Lowbie snipers are incredibly overpowered in 11-29 (honestly, I think that's one reason people are always harping on snipers at 55, where they're much more balanced -- traumatized first impressions stick). Snipers start out with their hardest-hitting attack, a 35m ranged root, a hard stun, and a 35m AOE mezz. They get a single-target knockback early if they spec for it and a powerful defensive ability in ballistic dampers. By the early 20s, a sniper has all
of the classes' most important defensive and utility abilities (entrench, knockback, root, flashbang, even evasion). The sniper even has a 30m execute at what, level 20? Other classes will get tools to deal with these things...eventually. In the 30+ brackets.
Other classes don't get their executes until the 40s. Warriors don't get their AOE mezz until level 42. Snipers have all the tools they need to stay out of reach of melee, and do decent DPS. Meanwhile, none of the healers are able to heal worth a damn. Etc.
It's a bit stupid, really. I wonder what Bioware was thinking. The only thing snipers are really missing from their main ability list is Series of Shots, and really, you don't miss the DPS that much. (The Big Bubble and Orbital Strike are nice, sure, but they're not central abilities the way Undying Rage and Force Camo are central to marauders.)