Yeah, a team that didn't even make the playoffs had a good chance of winning the WS making that move, good call. And

at those players not being a key part of the Rangers run. Feliz was their freaking closer and Harrison was their second best pitcher in 2011.
I would agree on Wainwright being a bigger loss overall, I consider those trades equally bad, with the Drew trade having a more lasting impact.
I think you are getting close to being rather disagreeable.
Matt Harrison was terrible in 2008, 2009, and 2010. He was decent and probably fortunate in 2011 and 2012. He struck out 126K/185IP in 2011 and 133K/213IP. Projecting alternative realities is difficult. Would he have been on the Braves in 2010 or 2011 or 2012? I'm not sure. Maybe? In any event, he was terrible every year following that.
Feliz was a perfectly decent closer several years after the trade. The Braves closed with Billy Wagner and Craig Kimbrell in 2010, 2011, 2012. Feliz would have been a nice set up man.
When Andrus was traded, the Braves had Renteria and a young Escobar on the roster. Andrus was further away and it was questionable that he would ever hit. I guess if you knew in 2007 that Andrus would become a hitter and that the Braves young SS Escobar would implode all of a sudden four years later, you might have said "hey, we better hang on to this guy" but I don't think anyone really knew that.
Salty never amounted to anything. I don't even remember who Beau Jones is honestly and I keep forgetting him each time I think of the five guys.
Finally, Feliz and Harrison were, as I said, nice complementary pieces for the Rangers run. But neither one of them was the reason the Rangers were good. They just were not. the Rangers slugged their way into the playoff with a strong lineup with fairly average pitching.
I'm not here to say that those players might not have helped the Braves four years later to some degree. I'm just here to say that the Braves traded some prospects who turned out to be pretty good for two years of Texeira and to strengthen the bullpen in an effort to win.
It seems as though you might have an issue with any trade that gives away value, no matter how significant a value, down the road for short term results. If so I disagree with you. I would trade a surplus SS prospect, a reliever prospect, and a back rotation starter prospect with middling stuff without too much hesitation if I thought that it might give the team a chance to contend.
It's baseball and sometimes you don't get the result you want. I'm sure the Braves were disappointed they crashed down the stretch, but if I recall they had some regression to the mean of some of their back rotation starters that contributed to that.
Sometimes players outperform, sometimes they underperform and you just don't always know which it will be. I do know the Braves traded for a guy who did nothing but perform at the level they should have expected him to.