I just noticed this today as well. Live in Phoenix, have the second highest tier of Cox and my latency jumped up to 80-90 ping in game. Oddly enough, I can ping their supplied server IPs and I get similar latency as what I'm used to, leading me to believe this is somehow client related, but seeing as how there is almost no reporting on this it's hard to say.
And before anyone starts linking all the crap RIOT provides, I went through their entire troubleshooting guide multiple times and have done my own work settings up my DNS and updating ALL drivers. This is replicated across multiple machines across my network with the same OS, but different hardware. Considering the fact I can manually ping RIOT servers at 65ms, but in game it's over 80 is highly suspicious. I'm used to shit ping failing every once in a while(all ISPs are monsters and deserve to be buried alive in greasy chicken fat) but normally I can replicate the latency issue with my own ping/network tests to throw at the techs who come out to inspect me "perfectly fine line". I'll admit I'm not a network guy, but I've done my research in terms of troubleshooting network specific issues and something isn't lining up.
And as far as "issue is the state itself", no. My mother in law that lives in Peoria gets 50ms stable when she plays, and she has like 4 other teenage boys hogging the bandwidth streaming HD skinflix.