Over in the comments at VEB I posted a notional chart that attempts to illustrate the “there’s no such thing as a pitching prospect” adage. The basic idea behind the chart is that pitching prospects will have a lot more variance in their projection that would hitters. This additional variance leads to a lower mean projection if you want to assume that two players have the same peak and same peak probabilities (i.e. both have the potential to be 6 WAR players). Here’s the chart I used to illustrate my point (the values are completely notional)
In this case the red is the position player and the blue is the pitcher.