So I've played for 2 days now. Quite a few times, I know I dodged something and the kill cam shows me just standing there. So I google it and... Overwatch has a tickrate of 20? It's like playing a 90's shooter again.
Tick rate has nothing to do with that. That is pure latency from the aspect of the shooter.
Tick rate is basically the commands being sent per second. The upload rate is 60 commands per second. That is how many commands from the client to the server can be sent during a 1 second upload package. The server sends back 20 commands per second.
Now normally most people actually aren't sending all 60 commands. For example holding down the W key to move forward with the SHIFT key to sprint while pressing the fire button all at the same time sends multiple commands of the W along with the SHIFT command key along with the mouse movement. There are also a sundry amount of other commands not exactly related to the player pressing a button that are sent.
Much of the Blizzard is streamlining their code from the server to handle latency issues with some people by reducing the return tick rate of 21 commands per connected person. Which means if there is 12 people in the game you are getting 11 X 21 = 231 commands in a single update package. Those packets contain more than just those commands though. Still, most of the commands being sent from a given client is are really not needed and don't make any difference in terms of play back. People like to equate the tickrate to frames per second, but they are not the same.
What you are experiencing is the side effect of a "favor the shooter" model of game design along with playing against someone with bad net latency. The person that killed you has a bad connection to the game and is in fact not receiving many packets from the other players. Which means if a few seconds worth of packets aren't being given to a player then that means several of the people around that player on their screen look to be standing completely still.
This is where favor the shooter sucks for good latency players and is great for crap latency players when they are mixed together. The bad latency player gets to shoot at standing targets and the server will for the most part ALWAYS allow the hit.
The killcam is just the repeated uploaded footage that the player saw when they made the kill against you. So you get to see yourself standing still on their screen.
The tickrate issue is blown way out of proportion and doesn't affect most players unless everyone in the game has great internet with low latency to the servers (talking 20ping or less here). Then the tick rate starts to make a difference in some regards to smoothness of movement with less interpolation needed.
Here is the Overwatch developers talking about the netcode here.
https://www.youtube.com/watch?v=vTH2ZPgYujQ
This is why I laugh at people that think the tickrate is what makes killcams look like "aimbots" and think that a killcam showing a snapping motion that makes the cursor move inches across the screen is a side affect of the 21 tick rate. The answer is that is not the case. There is some
"possible" interpolation of the movement going on from the other persons client but any potential snapping interpolation would be shown as pixels on the screen and not large movements at all.
More discussion here.
https://www.reddit.com/r/Overwatch/comments/3u5kfg/everything_you_need_to_know_about_tick_rate/