I’m hoping these guys make it but history tells us that most of our good mids were best 22 by the time they were 20, eg, McGrath, Heppell, Parish and Stants @ 19yo - all high draft picks I know - but also Merrett and Zaka (and Fanta) at 20 - all 2nd+ rounders.
Most of the players that have taken longer have been serviceable b-graders, eg, Myers 22, Colyer 23, Howlett 23, Hocking 22 and Dyson 21. Watson is probably the only exception (@ 21), but he took a bit longer to get his body right.
Even Melksham and Jetta were getting regular games @ 20 (albeit in weaker sides).
Anyway, let’s hope 2018 is a breakout year for these two (and Big Red).