I like this idea but we could take the test process a step further. How about players who are new to ranked are queued with a team full of ribbon users or players with 100+ games on the enemy team that will provide the test if you will. This game isn't worth lp to the people playing it is worth bonus community recognition. Also if you participate in this testing process as a pseudo coach you can earn an icon after so many times.
The players on the pseudo coach sides job is to play the game regularly and evaluate a players mechanics and other things after the match is over the player can click pass or fail as a option. This doesnt mean the player failed if he gets a fail hes allowed to try 5 times in 1 day out of those five he must get 3 passes. Players that get a pass have to receive 2 more to go on as well just to make sure its not a lucky streak.
This would let players have a real kind of coaching before attempting ranked play and get some comments on areas to work on as well. There's a lot of ways to develop a test system and yes this could be abused by trolls but im sure riot can figure out a way to make it not a troll fest. This kind of system could also replace the placement match system by making the enemy team judge an enemy player when they are trying to climb the placement match.
For example lets say you hit gold placement and you are silver the enemy team is made up of all gold players and win or lose your fate is decided by how you performed in the match and if they give you a pass grade. So this way people are judged on individual skill not just a team who doesn't work together or rages at each other.
All these ideas seem like they can be abused and yeah they probably can but hey just throwing it out there.