LP Question

So I started playing ranked the instant I hit 30 (I know, terrible decision), and dropped to bronze five almost immediately. One of my higher ranked friends told me i should play some more unranked, and get some experience before trying ranked again. I followed his advice, and am starting to carry myself out. My question is that for the first game or two I won, I got ~20 LP for it, but now I'm getting ~5 even though I have around a 75-85% win rate since I've been doing ranked again. Why is this?