6 injured players in 2 days is a bit of bad luck, but injuries are very common on Top Eleven so don't be suprised if it happens again, the good news is the maximum number of players you can have injured at anytime is 7.

L7 Stadium does not reduce the possibly of injury, Its the pitch playing surface that does.

Unfortunately the good youth players cost tokens and since they came through the youth ranks I don't believe that we should be paying any tokens to hire them either, you can buy good young 5* players from the transfer market that other clubs sell and you can normally get them for much less than 30 tokens.