Good call, let's analyze.
Beltran was owed about $5M at the time of the trade. He was about a 1-2 win player at the time of the trade, so could have been projected to produce another 0.2-0.4 WAR in 2 months, which is worth $1M-$2M. He had a negative surplus value of $3M-$4M. The Yankees had to kick in $2.5M to facilitate the trade, which essentially brought Beltran's surplus value to 0 (odd how that works out, right?).
In exchange the Yankees got Tate (50 FV) and a couple guys that don't even crack their Top 30. The only piece with value was Tate, but that is a lot of value to get in exchange for a player with essentially 0 trade value. It should be noted just how well the Yankees did at the deadline last year.
That is the "contender's premium" teams pay at the deadline because they know they have a good chance of using that player in the playoffs.
So if the Braves find a team in the same situation the Rangers were in last year, they could potentially pay down $10M-$15M of Kemp's salary to get his trade value to 0, and get a low end 50 FV guy like Tate as the return. I seriously doubt Coppy trades Kemp under such a scenario.