Juco guys under what coach? Lots of them panned out under Sampson and Tubbs. Very few did under Capel. Just looking at Sampson off the top of my head I recall Everett, Taj Gray, McGhee, White, Brewer, Johnson, Erdman, Abercrombie, Avila, Selvy, Dietrik, and Ere all making pretty big contributions. I suspect I have forgotten a few names, especially in the 90s. (for those that say Juco is different now, I offer Baylor's Jackson as Exhibit 1)
Under Kruger, I would contend that Grooms panned out. I suspect Arent gave Kruger exactly what he thought he would get. OU had a very thin roster, needed some size and didn't have a lot of options. If nothing else, Arent gave OU size in practice, especially two seasons ago. On top of that he gave some minutes his first season and rebounded a bit. He didn't play much this year but he had Osby, M'Baye and Fitz in front of him. There is not a lot of shame in not playing in front of those three guys.