I got the same phone from Verizon about 3 weeks ago and had similar issues at first. Note that the problem is on WIFI only. I am not sure why, but for some reason it seems to have diminished over time. Looking at it right now after being on WIFI in my house for about 6 hours, cell standby is at 3%. It used to hover around 25-30%. My cell signal at the moment is hovering between 2-3 bars. Your screenshot shows only 1 bar, so that could be the issue.
I tried disabling HD calling and that didn't make any difference so now I keep it on. You can't be on a call and use data at the same time if you don't have it enabled!
Another thing I did was follow the De-bloating thread on XDA forums. Installing Package Disabler Pro and disabling a bunch of bloat has increased batter life, and who knows, maybe helped with this standby as well.