I dug into this (Belt vs Santana) for dot com. I went back and forth on the conclusion a lot but eventually settled on one of the two.
http://sonsofsamhorn.com/baseball/majorleaguebaseball/al-east/boston-red-sox/red-sox-pursue-brandon-belt-carlos-santana/
Solid read.
I think Belt's 4 year commitment would have to figure in there too, at least given possibility that Santana doesn't get that many, and with the surrounding chance we might end up wanting to hit somewhat of a reset button on roster construction halfway through that contract period.
You also have Santana's fairly recent and visible HR upside of being a 30+ guy ( hitting 34 in 2016). Which contrary to some beliefs in this thread, as they vehemently point to his ISO/SLUG #'s claiming it shouldn't matter, probably does indeed factor to how DD or another GM is going to view the fit under a better case scenario lens and in relationship to their current roster construction (especially those in need of more homeruns, and which also plays towards why Belt would even be available for trade in the first place).
Then of course you have the overall sell factor. Which again I completely understand why people are going to vehemently insist that this shouldn't matter...and maybe/hopefully it doesn't. But it is worth at least noting here that DD would probably take a bigger "we needed HRs and he overpays for another SF castoff who's never even hit more then 18 of them" winter beating of the two outside this board and in the media in the event Belt ended up being his off-season solution to fixing our power starved offense.
