Kirk's struggles to recruit at the WR position are at least mildly understandable - a philosophy of ball control, run first mentality, no emphasis on setting up for the big play, etc. - but, with his reputation, and Iowa's history of putting linemen into the NFL (particularly from '02 - '10), his struggles at recruiting along the OL are more vexing.
It's hard to pin-point the problem, but he has struggled for years bringing in top targets. We've lost out on numerous recruiting battles, and have been forced to rely upon low-ranked or walk-on projects much more than we should. Perhaps that's by design: It's conceivable that Kirk actually prefers to bring in the projects and build them up. The problem is that when attrition occurs, we end up forcing guys into regular PT that are not ready.
Like recruiting in general, that does appear to be improving. Wirfs, Kallenberger, Jenkins, etc., all appear solid, and, we have a good start with the '19 class. Either way, there really is no good excuse for Iowa not to be stacked with solid talent waiting in the wings every season.