According to Ken Rosenthal of Fox Sports, quoting the ubiquitous major-league sources, "The Reds' trade discussions about [Brandon] Phillips include a proposal in which he would go to the Diamondbacks for second baseman Aaron Hill." He does immediately acknowledge that there are a number of potential issues with such a deal, not least that Phillips would have the full right of veto over such a deal, being a ten-year player who has played five with the same team. This may be why negotiations, per the piece, "have yet to progress to a serious stage." It also doesn't help that Phillips is earning $1 million more than Hill this year, and has a $14m contract for 2017.
Phillips has been solid rather then spectacular offensively over the past few seasons, with an OPS+ in the nineties each season since 2012. However, his overall value has been decent, averaging about 2.7 bWAR in that time, and better than that (3.5 bWAR) in 2015. Hill, meanwhile, has fallen off a cliff since the end of 2013, being below replacement level each of the past two years. One imagines the Reds, who went 64-98 this season, would prefer to have one year of Hill and be freer to rebuild, rather than two years of Phillips.
From the D-backs point of view, getting a semi-decent second baseman would likely free up Chris Owings and/or Brandon Drury as potential trade chips as we pursue the team's main goal: improving the rotation. In a second article, Rosenthal thinks we "ideally want to add two starting pitchers," but agrees with the general consensus that the top of the free-agent market may be too rich for us. I also note that the Indians, one of the teams mentioned as a potential destination for A.J. Pollock, are now in greater need of outfield help, with Michael Brantley now out for at least the first month of the season.
Rosenthal says if talks progress further, "The deal could grow to include other players as well as some kind of financial exchange." A reference to Aroldis Chapman? Though opinion on whether we are in the market is divided. Jon Heyman says Arizona "seem intent on acquiring a closer, and with so many available in trade and a nice stash of positional players, the smart money says they do." But in that other piece, Rosenthal says the Diamondbacks "now seem content to keep Brad Ziegler in that role and build the bullpen in front of him." He also quotes a club official saying teams are "all over" our outfielders, with infielders also drawing interest in trade discussions.