This is why most experts feel, you should never transfer to Delta unless you really need Skymiles. They have been having a perpetual 50% transfer bonus for first time transfers from Membership Rewards (MR) to Skymiles. The last offer just ended on May 31 and the new one is back already for transfers until Sept 30.
The only difference is that unlike last time, the threshold for getting 25K MQM (and hence Silver status on Delta) has been raised from 50K to 100K MR points transfer. Still, a good deal in case you need Skymiles. Contrary to popular perception, Skymiles are very much redeemable. The only problem is that it takes a lot more legwork compared to other award redemptions.
To take advantage of the offer, register via http://dmn.delta.com/ace_offers/junemr/prior to making the transfer. In case you have already transferred before, there is a 40% transfer bonus if you register here.
(HT: Gary from View from the Wing)