Del Zotto has only 9 points through 35 games. Sure its more than Gilroy sauer and Eminger, but after a point every other game last year, its not enough. Not to mention the latter 3 are more reliable defensively (that is in no way knocking DZ's defense, I have been fine with him despite his lack of production).
That being said, he is one of the Rags top 4 dmen. So Im not sure why they would send him down, I think it may be more a matter of stellar play from 'Mickey D' (whom I saw on New years day in their romp over the Bruins).