He is in midst of a nasty slump that has carried over to the field. However, (I have him on my team, and I am an avid Twins fan) it is hard to see him struggling so much. There are some thing that are nice to see. Those being his Triples and Doubles and his increase in Walks. Last year in 645 PA he walked 26 times for a 4% walk rate. This year in 198 PA he has walked 17 times for a 8.5% walk rate. That is double what he had last year.
I know he hasn't homered in over (IIRC) 60 games dating back to last year. However as several people pointed out already he is only 22, and few 22 year olds mash 20 hrs a year. It is more important to develop his swing and mentality at the plate. And to the person that said they thank the Twins for the trade. Remember they don't just give pitching away. Usually they are the ones that end up with the better end of the deal. Look at the Milton deal, the AJ deal, and the Knoblock deal. They end up with the better prospects in the end.
Delmon Young is still young and has many years to develop his power, and it will come. I will predict about 10- 14 this year. Much in line with what he had last year.