That doesn't mean they need to do as the Tigers did with Gary Sheffield and eat the entire contract or work out such a long term payout that they'll be paying for him until he's in his fifties like the Bobby Bonilla arrangement.
The 2B market is extremely weak so even after proving he can still be a solid table setter nobody is willing to take Castillo at full value and it doesn't appear that Omar has been willing to take a worse contract or pay a significant portion to move him. If bringing in Hudson means Castillo has to be gone then Omar might need to get flexible with his trade demands, something like taking on Gil Meche contract and throwing in 6MM.
But signing Hudson might resolve this matter in itself, Castillo either becomes an expense bench player or he goes to the Mets and works out a release. With Hudson on the team the mets have the upper hand, unlike in the Bonnilla negotiations where they were begging him to leave. By the way Bonilla will get his first installment in 2011 for those who don't rem. he deferred 5.1MM for 11 years with interest and will get paid 1.2MM per year for 25 years, equalling approx. 28MM.
Look if the Angels can afford Matthews Jr. on the bench while last year paying Vlad, Abreu, Hunter and Rivera; or the Dodgers can move Jacques Jones and renegotiate A. Jones to release him; or the Tigers can cut Sheffield and the Sox can sign Beltre with Lowell still on the roster then the Mets can do something with Castillo.
An added incentive of signing Hudson would be to avoid allowing him to go to the Nationals.
Assuming the Mets are stuck with Castillo, Hudson's market could be as weak as it was last year. The Nationals have shown some interest, and while he managed to avoid them last year, he might not be able to do so again. He would probably take the $8 million he made last year but may again have to settle for a deal in which half is guaranteed and half has to be earned via incentives. source SI.com