Unfortunately ISU is not a blueblood and whether we like it or not its not easy to just reload. It's never been easy if you've been following ISU. Hoiberg did it through transfers before transfers became a thing....he couldn't do it now if he was still here. I agree, the expectation should be fighting for an NCAA tournament bid/top half of Big 12 every year. If Prohm doesn't do that next year, I think he's gone.
As for the 17'-18' year, I think most people understand how unique the situation was. Prohm did have time to prepare, but he was way behind the wheel with A. Hoiberg leaving at a very tough time for recruiting and B. Hoiberg basically missed a year of recruiting that set the program back. That unfortunately doesn't always rear its ugly head until down the road.
Not only did Hoiberg not give Steve time for recruiting, but people also have to remember that Hoiberg changed the landscape of Iowa State basketball. He made them relevant. So, when he left, I can assume recruits were a bit reluctant in going to Iowa State right away because Hoiberg was gone.
Now, with that being said, it's still Prohm's job to recruit and the blame still deserves to be on him for that '17 / '18 year. He definitely made up for it by being able to bring in THT, Tyrese, Conditt, and Shayok and having a pretty good year last year, but when 5 players leave whether for graduating or to go to the league, it's going to be an up-hill battle to try and get back to where you were the year before.
I think that Prohm knows he struggles with recruiting on the fly. He's had some very good recruiting cycles, but also has struggled when a curve ball gets thrown at him. What if a couple of the guys next year do extremely well, we make a splash in the tournament or do very well, and another two guys leave? I just don't have much confidence in Prohm with how he he's handled guys leaving when he didn't expect them to.