I would actually argue that had Book been the starter full tine in 2017, Equanimeous St. Brown would have had a fantastic season, instead of almost having his neck broken several times trying to catch errant Wimbush passes.
I'd even guess that St. Brown would have stayed for 2018, which would have given us a much stronger WR corps.
As it was, in 2018 Miles Boykin had a nice season as a WR1, and got drafted in 4R. Claypool as a WR2 was a solid player, and Finke was a good WR3. This was a direct result of Denbrock having brought them up.
Chase Claypool had one of the best seasons as a WR1 and got drafted in 2R. What was unusual, though, is that Finke was our WR2. That right there showed terrible development of the recruited talent. Basically, most of the guys that Mike Denbrock had recruited and developed were gone by this time.
Del Alexander stunk as a WR coach, and the WR development degenerated once he was in full swing.
In 2020, Javon McKinley did what he could, and was a serviceable WR, but he didn't have much luck beating the better CB's. When Ben Skowronek, a transfer portal guy, basically beat out our home-grown talent (Lenzy, Keys, Wilkins) for that WR2 spot, it was once again an open sore on our WR recruiting and development.