Assuming these rumors are true:
The Mariners according to Geoff Baker, would have gotten to choose the five Red Sox prospects among a list of eight. Those eight included RHPs Clay Buchholz, Justin Masterson, Michael Bowden and Daniel Bard, LHPs Felix Doubrant and Nick Hagadone, SS Yamaico Navarro and OF Josh Reddick.
The 3 way deal intrigues me more from a M's perspective. Of course the 2 Red Sox prospects are the key, who are they? Also I believe the M's would have had to trade prospects in this deal, Truinfel is a name I think I read was rumored in this deal going to SD.
I agree with the M's holding onto Felix, but I wouldn't have hung up the phone feeling insulted with either offer. With that 3 way, depending on the details, I may have been interested in working on that. The thought of trading Felix Hernandez makes me nervous, even just pretending to be the M's GM.
Edit: I think the rumors were Truinfel and Morrow going to SD. I wouldn't entertain tht offer if that's true, even though I feel both prospects are overrated in their own way.