I did a silver V > Silver I climb last month (Started at bronze IV) then inted down two divisions every time I hit gold promo but I've been up and down in the silver bracket many times recently so I know what you are talking about. If the game isn't a blow out either way it is always decided by who ints firsts / who ints the hardest. Silver is full of huge egos on both teams so try to harness it to your advantage instead of letting it be random. I got a few strategies I use to ensure the other team tilts harder and earlier than mine:
Use thumbs up emotes anytime a team mate does something good, like land a skill shot, take a tower, get a kill, do a good trade. Put regular thumbs up, and teemo thumbs up (Maybe Lux excited face can work too.) on every spot of your bar but never use them sarcastically in a solo situation (Makes you look upset/edgy, or that you are equal to your opponent). Enemy team gets very tilted when you are congratulating your team mates for doing well with emotes.
If you escape a gank or team fight or delete someone, type cya or "CY@" into ALL chat which tilts most of the enemy team every time (Especially if there's a lucian). Half the team will dive you every fight to try and kill, just run backwards and let your team clean up. If they wind up killing you while diving type "WORTH" into ALL.
In silver everyone loves ALL chatting about how they think one of their team mates is bad. Abuse this phenomenon since it happens every game it's a easy way to secure a win. Agree in ALL with the accuser even though they are being toxic and even if you hate that behavior r (point out low cs, or low kda, or whatever). Don't stand up for the accused even if you want to. It makes the accuser not play hard anymore and it causes the team to gang up on the accused who then ints and gives up, the team will spend the rest of the game typing into ALL telling you who to report on their team and will not focus anymore. If you try to stand up for the team mate getting abused it creates an underdog effect and unifies their team.
Let them win at being a bully while losing the game and their LP to you.