Putting aside Ruffels, Long and Baptiste who have already come through recently, and either established themselves and/or went for decent money and Napa (sans injury), Carroll, COD before them, I guess top of the breakthrough list for this season is Jack Stevens who is now a fully established senior squad member.
Then, even if Jones (18) has stalled for the moment, we have Lofthouse, still only 19 (I think) whose versatility may prove useful slotting into the lineup at various points.
Then come this summer's other graduates (ie. 18) - Lopes, Spasov, Elechi - and second year scholar (17) Ty Goodrham who have all already tasted the senior bench and will probably do so once again this year too, so the pipeline is there and is functioning well.
Don't forget COD (& Long) was probably the first one to come through from the Lenagan-revived system after FK had stripped everything back, so there was a lot of momentum needing to be restored