overwatch – Does Winston’s Tesla Cannon Penetrate Zarya’s Barriers?

His damage is one of the lowest (if not the lowest) in the game. Here is a relevant quote mentioned by Blizzard developers (This is in reference to D. Va, but the Winston mention is specific).

D.Va's damage is definitely on the lower side, much like Winston's. They are this way for a similar reason: They are both very mobile and hard to kill. Every character in the game has strengths and weaknesses, its part of what makes the teamplay work well.

Source: http://us.battle.net/forums/en/overwatch/topic/20744914371?page=3#post-43

As for "missing" something about the mechanics of Winston's cannon, there are a couple of things to keep in mind.

1. It's an AoE. His cannon can hit multiples targets in front of him. It's a fairly small cone, but it will hit more than one enemy at a time if they are grouped up.

2. There is no need to aim (mostly). His cannon doesn't really need to be aimed, just pointed in the enemy's direction. It can hit blinking tracers and such with nothing required except making sure you are looking at them and within range.

3. His jump also does some damage. Minor, but if you jump ON your target, they take damage, then you burn them with the cannon and can jump away if it looks like you're losing, which ties in to the developer reasoning above.

Explicitly to answer the question, Winston's cannon will do more damage by hitting more than one enemy at once. Winston isn't bad overall, but he is bad at dealing damage - that is NOT what he is designed to do.

According to the [WIKI] it does protect against all stuns and knockbacks.1:

Particle Barrier: When activated, Zarya will completely surround herself with a barrier for a brief period of time, absorbing a large amount of damage and making her immune to all negative effects (such as knockback or stun) while the barrier holds. Damage dealt to the Particle Barrier contributes to her Energy.