The balancing act when trading for now but not getting burned in the future
There is always a risk when making a trade in any sport, especially baseball. It is usually less risky when making a player for player deal as, for the most part, with established players you have a pretty good idea what you are giving and what you are getting. Also there is less of a financial penalty because there is no salary cap. A deal may hurt your budget but not necessarily cripple the team. Of course injuries that may crop up are out of anyone's control. The Ian Kinsler/ Prince Fielder trade between the Texas Ranger and the Detroit Tigers is evidence of that. Tigers look to come out way ahead of that one so far with Fielder possibly out for the season with neck surgery.
Where deals are a little more cloudy is when you start throwing prospects into the mix. This happens a lot near the trade deadline for teams that look to get an established arm or bat to help in a push for the post season or for a World Series run. Eliminated teams will often deal top end players that will not help them in the short term and get top end prospects to help them get better in the long term. It is a tough balancing act on how much teams are willing to give up in terms of the future for players that can be dropped into the line-up right away.
Every team has stories about winning and losing deals with this practice. As a Braves fan I know all to well that one can hit a huge home run when the prospect that you trade for becomes a soon to be Hall of Fame member. It started with the Braves trading Duane Ward to Toronto for Doyal Alexander. Then Alexander was traded to the Tigers for Prospect John Smoltz. Not a bad deal, Alexander went 9-0 and helped the Tigers win the AL East, Smoltz went on the be part of one of the best rotations ever assembled in the last 50 years. There is also trades that looking back involving prospects that look less then favorable as a Braves fan. 1 Career year for JD Drew and Eli Mararo to the Braves for competent reliever Ray King, Jason Marquis (who was still decent at the time) and, this is where it hurts - prospect Adam Wainwright (he turned out pretty good). The other prospect trade that looks bad now was the deal that brought Mark Texteria and Ron Mahay to Hot-Lanta for Beau Jones, Elvis Andrus (Starting SS-close to 30sb per yr), Neftali Feliz (40 saves in 2010), Matt Harrison (won 18 in 2012) and Jarrod Saltalamacchia.
The best trade of late that was not made was the deal that would have sent Randall Delgado to the Cubs in a deadline deal that would have seen Ryan Dempster sent to the Braves. Thankfully Dempster vito'd the trade and the Braves retained the rights to Delgado. Delgado was then used as a key piece that brought Justin Upton to The ATL with 3B Chris Johnson for Nick Ahmed (minors), Brandon Drury (minors), Randall Delgado, Martin Prado and Zeke Spruill. Had Delgado been traded to the Cubs for 1yr of Dempster the Braves may have had to include Julio Teheran as part of the Upton deal. Not something the Braves I imagine would have either wanted to or would have been willing to do.