I would be careful with the broad absolute statements like that. The staff has some major league successful stories in Moses and Jose - and several nice development stories behind them. Howard and Saba look good so far but still early against middling competition. On the other side CJP has taken a whole lot of projects that haven't worked - from Haywood, Sjolund, Didenko (the Russian assasin), Price and could even throw Maxwell and Moore in there.
Nobody has a 100% success rate in terms of developing talent. There will always be guys who don't pan out for whatever reason. However your examples kind of help support the point that Pastner develops players well. Several of those are reaches as far as evaluating development goes. Maxwell has been here just over a year and was hurt for the majority of that time so how can you possibly judge his development? Didenko was a reach from the beginning and we have no real frame of reference to judge any improvement or lack there of because he never really played. Sjolund and Price were here for about a year or less so there is no real comparison of before and after to make. The best counter examples are Haywood, Moore, Parham, and Cole. Haywood got better defensively but never really seemed to find his stroke after his freshman year injury. It's hard to really comment on overall development since he left after just 2 years. Moore and Parham have both developed okay but not the same level as the others. Both settled nicely into the roles that helped the team but not really anything noteworthy. I'd argue Cole is the best example as he really didn't seem to develop too much over the course of his time here. He had marginal growth but it felt like he had potential to do more than he ever really did.
But for next year we don't need everyone to have tremendous development. Guys like Coleman, Kelly, Sturdivant, Smith, and Howard will likely have natural development getting playing time this year and then we also have guys like Saba, Meka, J. Moore who could develop behind the scenes a good bit as well. Our staff hasn't been perfect on player development but the relatively high % combined with the volume of young guys to work with is a good combination.