Not necessarely - if you are training guys that have been trained for a while, you might have a guy with like 20k salary at 21 years or something and they would very much be able to hold their own.
I have two players like that so in league games I just play them giving them 32/16 minutes each and it works out alright.
But yes, if they are 18 y/os you pretty much play them in scrimmages.