Clemens was better in AAA than Dunn was in AA this year. Castro is 2 years younger than Dunn and has already showed he could be a platoon player in the majors.
We valued those guys over Dunn. I know you love Dunn, but the Phillies don't make this deal if they think Dunn is better than either Clemens or Castro. They think both players are better than Dunn.
It is possible we are interested in drafting a rule 5 player, but just as likely we know we will need the spots. We'll need one for De La Cruz if we protect him. And we'll need 3 spots for a starter to replace Nola, a reliever to replace Kimbrel, and a LF to replace Hoskins. Probably small chance we draft somebody but I doubt there is anyone we really love for a roster that loves to churn anyone on the 40 with options through their bullpen.