I look at all of these as upgrades:
(1) Trade Jerome Jordan for a 2nd round pick. Immediately bring in Marcus Cousin to fill his spot. He's flat out a better NBA center prospect and would be more useful for us. Much more reliable game that D'Antoni would be able to utilize -- he's an EXCEPTIONAL jumpshooter out to about 20'. Good FT shooter too, about 80%. Plus he can body up and play physical, hit the glass, etc...Real solid jump hook and a smooth turnaround jumper in the post too...Where Jordan is the ultimate wildcard that just feels too green and inexperienced, this dude's entire game feels much more NBA-ready to me by comparison. Doc Rivers is starting to incorporate Purdue's JaJuan Johnson more and more now in Boston; I actually think Cousin has similar only better overall skills and he's bigger and stronger than Johnson (more of a true center at 6'11.75" 250+). I believe in this guy's game -- I honestly can't believe Cousin's not on an NBA roster somewhere right now.
(2) Either trade Walker (maybe in a package with Toney Douglas) or just flat out cut him/buy him out to open up the roster spot. Bring in either Manny Harris or Mo Almond (good call CA7) to replace him and back up Fields at the 2. I'd also take a real close look at 6'7" 215 SG/SF Mychel Thompson (Klay Thompson's brother) who was just cut by Cleveland. I know there's little to no evidence to support adding Thompson considering his 4-yr career numbers at Pepperdine (particularly the low FG%) and his cup of coffee with the Cavs were both underwhelming, but I dunno man, I see some good skills here with this guy, similar to his brother Klay. Listen, I know he's not Klay, all I'm saying is they play the game similarly...He actually played pretty well in the DL for a few games this past December and he did make that Cav ball club outta training camp which tells me he must've shown them something -- maybe the kid's a late bloomer and we could catch some lightning in a bottle.
(3) Find a way to clear one more roster spot (which is why I'd look to pull off a 2 for 1 trade for a player we could immediately cut or for a future pick we could tuck away for the time being --- maybe we look to package Jerome Jordan/Walker, Douglas/Walker, Jordan/Douglas --- and add one more frontcourt big, maybe one of these 3: Darnell Lazare, Greg Smith, or Marcus Lewis. Lazare's got a real good offensive game (post up, puts it on the floor well, reliable pick & pop jumper from 15-18'); Smith's a grinder that'll battle hard in close and so is Lewis, who's a very good rebounder and a double-double machine so far in the DL this yr.
Let's hear some more ideas -- minor roster moves to help better the club.