I have account in silver, and my main is platinum. With my main champion I have trouble in silver cause of bad players..very often....I recently got demoted to silver 4, and my main account is plat 5 and it's being ranked up.
I was trying my best in my silver games just teammates where bad. I'm not sure at all why this is. I assume it's maybe because of my case, ppl have second accounts in a lower rank than their main, and troll on their second account. That's my guess.
Or it may be cause it's too late to rank up. The better players ranked up, ppl from bronze or new players (learning still) are trying to rank up and you're stuck with them in silver. To rank up in silver look for an op champion, that can win a fight 1v5 lol and is hard to focus down. There is no team play in silver right now.