Let's say we get to the SB and pick #31. That's 600 pts.
#22 pick is worth 780 for a total of 1380 pts to deal up with.
That would net you the 8th or 9th overall pick which are 1,400 and 1,350. Doesn't sound that bad when you're that high, but the point value skyrockets when you approach the top three picks at 2,200, 2,600 and 3,000 points.
You would essentially need two lower top ten picks to get to #1 or #2 which we don't have. Tacking on 2nd and 3rd round picks only gets you another 400 points which still puts you way out of range.
Basically, to get to DMac, you're mortgaging your whole draft and probably a #1 next year. Way too much ammo to give up to get a guy who could blow out an ACL on any down.
I could see packaging the two picks and getting him at #8 if he dropped (not bloodly likely), but when the dust settles, we're just as well keeping our picks and getting a RB to split carries with MB and a corner who can takeover for Henry down the road.