Is na.op.gg's MMR checker accurate?
So I've decided that now is the time for me to start doing ranked to reach Gold V for the season rewards. I got out of bronze EZ PZ, and am currently Silver V 90 LP (I have high MMR so I've been playing mostly against high silvers and low golds this entire time, even when I was in bronze).
Yesterday I checked my MMR via this website, and the first time it said my MMR was average for the league I was in. Then I checked it again like 1 hour later (I hadn't played any games since then), and it says that my MMR is higher than average, and I might advance two divisions at once.
Then I check it this morning and it says my MMR is well above average and I will absolutely rise two divisions at once.
http://na.op.gg/summoner/userName=Laraso
At first I trusted the site but after that, I'm highly skeptical. Can anyone verify if this website is actually accurate or if it's flawed?