Yosemite WiFi performance - MBP

I have a mid-2012 Macbook Pro running OSX 10.10.4.

Ever since updating to Yosemite, the Wifi performance has been terrible. Connection shows full bars, but actual connection to the internet is spotty at best. Plugging in an ethernet cable gives normal performance, and all other devices in my home have no connection/performance issues (iPhones, iPod Touch, iPad, Lenovo laptop, Dell desktop w/ wireless card, WiFi enabled printer, etc.)

I've seen all the suggested troubleshooting, most of which seem to focus on poor connection. The computer never "drops" the connection, it just takes forever to transfer data (if it transfers at all).

I've tried resetting the PRAM, renewing the DHCP lease, changing the DNS server, and most other recommended fixes. Most recently, I reinstalled OSX from recovery. None of this has helped.

For reference, the Wireless Diagnostics/Performance tab is showing a massive drop in signal (RSSI) and quality when the MBP is moved more than 3-4 ft away from the wireless access point. When sitting adjacent to the router the RSSI is around -55dB. As soon as the MBP is moved further away, the RSSI drops to -70 to -80dB. Noise is around -90 to -100dB. Quality "number" (which I don't know where they get this from) changes from 35+ down to 20-25.

Any ideas would be appreciated.