Rojas might have some of the higher SP upside in the system. I don't think he's a backend SP prospect.
All of Yesavage, Tiedemann, King, Stanifer, Rojas, have SP3 upside or more. IMO.
Stephen and Bloss might be more like SP4 upside but you can imagine them being better; Bloss' stuff was popping before injury and Stephen might have sneaky good stuff and command that lets it all play up to SP3.
Obviously Maroudis, Barriera, maybe Messina, could be more than back end starters but it's too theoretical and remote for all of them. Just lottery tickets.
The system has so much going on that you almost forget about people. I don't know enough about Watts-Brown to slot him anywhere but he's not a boring prospect either from what I have read and belongs in the above discussion somewhere. Guys with RP or SP5/6 projections, you just don't even think about anymore. Guys like Connor Cooke and Chad Dallas use to almost crack the team's top 10 prospect lists. Adam Macko is barely hanging onto relevance.
Really, I don't remember the Jays farm system ever looking like this. Just so much going on. The Jays lead the AL East and have an exciting farm system at the same time. Wow.