I just think Bo Jackson is a really horrible example to use as a '7th round' pick that succeeded. There was no question on his talent, hence why he initially went #1 overall.
I agree with the idea that you would like to see Poles get better at finding some day 3 contributors. I think right now you can reasonably argue that he found 2 solid players in Braxton Jones and Terrell Smith, both in the 5th round. The punter in the 4th is a starter, but that is a given considering he spent a 4th on a punter.
I also think because he screwed up the initial coaching hire with Eberflus that his chances of hitting on a day 3 pick went down because Eberflus and his coaching staff did not appear to know how to develop players.
Time will tell if things get better now with a new coaching staff hopefully giving better evaluation input and also just better coaching if they can find some day 3 gems.