I don't think Pledger is a donkey, he has some attributes, but certainly he isn't as good as a lot of people are saying he is, he isn't one of the premier defenders in the league - for an NBA comp, he's not Roy Hibbert or Marc Gasol, he's more like Brook Lopez, a lot of shot blocking but nothing else really of substance.
I think Johnson will be the right recruit over time, I think he needs to work in the halfcourt but he's deadly in transition, and although he's not as good a passer as Cedric, he is a slightly different player, he almost does need to call his own shot occasionally as he's one of our few players who can create off the dribble.
Now, I really rate Vickerman as a coach, and he's a good defensive coach, but these interpretations, coupled with the defensive talent he's working with, it is really not ideal at all. Johnson, Webster, and glaringly, Wilkinson, are all well below-par defensively, with Wilkinson especially being a real minus on that end, which does strand Pledger a little bit at times, Pledger works well with Vukona, and another other PF really (Give Salt some minutes!), but defensively, him and Gary are not a good tandem.
Strangely, I still think we can make the playoffs, but four in a row is clearly not happening, and nor should we expect it to, it's been a superb run.