Look, I get it that it's cool to clown on Dunn around this board... but picking, what, 10 games to say he couldn't still hit in the NL is a bit ridiculous.
Isn't it also pretty ridiculous to assume that changing leagues is going to allow some magic mojo to descend on Dunn, restoring him to his former glory?
AL pitchers are selected from the same pool of candidates that NL pitchers are. Pitchers in both leagues are traded back and forth, become free agents, sign with teams in other leagues, etc. There's not some big dramatic difference between them, unless you believe in voodoo.