Mark Teixeira - 2007/2008
This is the one we had to fudge a little bit, but we promise it still makes some sense. During the 2007 season, Teixeira was among the best hitters in baseball and had just turned down the Rangers' attempts to give him a contract extension. So, the Braves sent a very hefty package of players to Texas for 1.5 years worth of team control of Teixeira.
Technically, Teixeira played in two different seasons with the Braves. However, it was only 157 games with the Braves as they traded him at the deadline in 2008, so we are counting it as one full season. After posting a 1.020 OPS with 17 homers in the 54 games after the trade in 2007, Teixeira would add a .902 OPS and 20 homers before Atlanta moved him in 2008 to the Angels. While this trade didn't burn the Braves too badly in the long-term, it was a reminder to teams to not give up too much for guys who are mortal locks to test free agency as soon as they are able.
Denis Menke - 1964
You are forgiven if you do not remember Denis Menke's six year run with the Milwaukee and Atlanta Braves in the 1960's as his time with the franchise was largely underwhelming. However, 1964 saw the infielder post the best season of his career as he accumulated 6.7 rWAR with a .283/.368/.479 line and 20 homers.
After playing three more seasons with the franchise, landed in Houston where he made a couple All-Star Games in 1969 and 1970, although neither of those seasons came close to the production he had in 1964. His career would come to an end after the 1974 season, but his work in 1964 still ranks as a top 50 performance (by WAR) among all Braves position players in the modern era. Not bad, Menke. Not bad at all.