Need a ranked matchmaking explanation

Can someone please explain why being in plat last season has now landed me with all silvers on my team yet plat on the enemy team? It has completely ruined my new season experience having players that do not talk, ping, respond, follow, ward. At one point the enemy adc even dcd...so they sent the mid support and jungle to push down bot the mid lane just sat at his tower...didnt farm, didnt push, didnt gank...nothing...wth am i suppose to do with that?