You can use the analytics to tell where the traffic drops are coming from but I think that you need to get to why Google or some other search engine traffic is dropping. So I totally agree with what EGOL mentions, but I think you already have a global grasp that traffic has dropped. Here are what I would suggest are next steps to then fix the issues of why the traffic has dropped.
Odds are is that technically you may have a problem going on.
Go through your GWT reports for crawl errors and HTML optimization etc. We relaunched and it gave us all kinds of clues on what to fix.
You need to double check all of your 301 paths - I bet that there are some holes. This is down and dirty detail work. I bet that they are probably not as correct as you think. Don't assume that if you test a few the rest are ok. Dont assume that the developer says that they are working that they are working. Run them through a tool to make sure that you are sending a 301 response. I had a site that was using 302 responses vs 301 (a temporary vs a permanent redirect). Verify, verify, verify.
Did you change title tags on your pages. Titles are a big signal and if you change them, you can see a drop. You can look at your traffic and ranking analysis to look at sample pages. If you did do a radical change, you may want to go back to your original title tag methods.
Run site speed tools
https://developers.google.com/speed/pagespeed/insights#url=www.brickhousesecurity.com&mobile=false
See if your speed has dropped. The GWT will also show over time if your site is speeding up or slowing down. You may need to look at your server setup.
Verify the HTML
http://validator.w3.org/
Did you setup
It looks like you may have changed a bunch of things at once and so it is hard to tell what you changed so see what was impacted. Usually in cases like this, Google is trying to figure out the changes and so it may take a while to sort out. I just gave some examples, but you need to review everything that has changed and see what the differences are. There are some things, even with a 301 redirects that are correct, if you changed the URL structure and title tags and the new site has HTML that does not validate, Google may take a while to sort it out. I had a site that we did a complete overhaul and it was 6 months before the traffic came back and that was with pretty good controls in place.
Good luck!