There has been a lot of Justin Upton news today as it relates to the Atlanta Braves. Will the Arizona Diamondbacks trade their star outfielder to Atlanta to be reunited with his brother B.J. Upton? First off, we got confirmation that indeed the two sides have been talking, even going as far as exchanging offers:

Confirmed that #Braves have indeed made offer to Dbacks for Justin Upton. I think Teheran plus 2-3 other prospects, but not sure

— David O'Brien (@ajcbraves) January 23, 2013

How fast could things move?

Sources: #Braves waiting to hear from #Diamondbacks on offer for Upton. "Sensitive" time in discussions.

— Ken Rosenthal (@Ken_Rosenthal) January 23, 2013

I'm not sure exactly what "sensitive" means, but it could have something to do with this comment by Rosenthal:

#Braves had trouble getting #Diamondbacks to return calls for much of off-season. As market for JUp shrunk, things evidently changed.

— Ken Rosenthal (@Ken_Rosenthal) January 23, 2013

I'm going to speculate that this might have something to do with certain Braves players or prospects being off limits in any trade talks. It could also have something to do with the package of prospects that Atlanta is offering being significantly less than other packages (specifically the one offered by the Mariners, which had several top-25 prospects).

So the "sensitive" in the above tweet could refer to whether or not the D-Backs think they're being bamboozled. Remember how many times the Braves and Padres went back and forth when discussing Jake Peavy? The Padres GM then, Kevin Towers, is the D-Backs GM now, so that gives you some idea of the gulf that could exist between what the Braves are offering and what the D-Backs might want.

The Braves don't want to part with any of their key pieces, and that may now include Julio Teheran. He being the best prospect in the Braves system, and the Braves not wanting to deal him, could be a pretty sensitive topic, for both sides. Rosenthal provides some ideas about the prospects that could be included by the Braves:

#Braves deep in young arms that could form basis of potential Upton trade. #Diamondbacks also like Gattis' power. SS Ahmed another option.

— Ken Rosenthal (@Ken_Rosenthal) January 23, 2013

Hopefully there will be more exciting developments to come...