This is basically a card game: Cincinnati has about 52 pitching prospects of various repute, and they need to find five of them that'll give them ~900 innings of not-embarrassing pitching. One can imagine the permutations flickering through Dick Williams' head here — is there any way for the maths to work out?
What do they know? Anthony DeSclafani and Raisiel Iglesias both seem to be pretty decent. Disco didn't quite break 200IP thanks to a rough September, but looks to be league average. Raisiel didn't quite break 100IP, but flashed a lot of exciting stuff in his first year in the United States. Them two, plus a Homer Bailey returning in June-ish is, best-case scenario, a bedrock of stability.
After that: choose your favorites from: Brandon Finnegan*, Jon Lamb*, Jon Moscot, Tony Cingrani*, Michael Lorenzen, Robert Stephenson, Cody Reed*, Jackson Stephens, Amir Garrett*, Seth Varner,* Nick Travieso and Keury Mella. Lefties are given asterisks. And if your favorite is Keyvious Sampson or Josh Smith, too bad.
What separates the above twelve dudes? I'll be honest, I have no idea. Lamb was poo-pooed as a back-end starter, but he looked fiesty (if homer-prone) to me. Finnegan is a bulldog, Moscot seems to have maxx pitchability, and Stephenson/Reed may be the next big things. We get to take all of Spring Training to decide, and really all of 2016. None of these youngsters are going to break 200 IP before 2017, realistically. Cincinnati will probably get a veteran starter to balance this all out anyways, but we fans basically get to go through Soviet-style training with a bunch of young fresh arms: throw 'em all against the wall and celebrate which ones don't break.
Even besides the ones I've mentioned, there is also Sal Romano, Wyatt Strahan, Mark Armstrong, and Tyler Mahle in the pipeline. Not all of them are going to work out, surely, but there will be interesting pitching depth up-and-down the system. You could even choose to get psyched up about Antonio Santillan and Ty Boyles if you so choose. Pretty much every start will have something that we could call "meaning" in a 2016 season otherwise devoid of it.
As for relievers, you'll have whatever fallout from ^above^ mixing it up with JJ Hoover, Jumbo Diaz, Ryan Mattheus goshdangit, and Rule Five LOOGY Chris O'Grady. Future Closer of the Future Zack Weiss might break camp with the team, as could the confusingly-named Stephen Johnson. The Reds will be in Year One of the Royals-track "create an evil bullpen via prospects with chips on their shoulders" in 2016. And if it fails, hey, there'll always be retreads and other prospects to fall back on. Come watch the sausage get made in 2016!