Don't take this personally, but I find many of your moves baffling. As an MLB manager with a long 162 games season, you are bound to face criticism throughout the course of a season from all sides, and I imagine it gets exhaustive. However, this doesn't mean there are not some quick, easy, and reasonable ways to improve the team. If you could consider these ideas to implement into everyday use, nothing would make me happier.
Move Pastornicky to the number nine spot. Tyler Pastornicky is a 22 year old with only a few dozen games experience above AA. His approach against major league pitching is an ongoing process. He should be able to hold his own at the shortstop position, while not setting the world on fire. You can't do much about letting a young player get his time in. But, you're not utilizing Pastornicky's greatest attribute! His speed. He hasn't even attempted a stolen base this season! He stole a considerable amount of bases in his minor league career -- and more importantly he did it at a success rate at over 77%. In this lower scoring run environment it is a bevy of opportunity. It's not like you haven't done this before. The Constanza/Bourn back-to-back did seem intriguing. Besides, it would likely allow Pastornicky to see better pitches while not hitting in front of a pitcher. That can't be good for a young player who isn't known for his patience at the plate. Having him in front of the pitcher incredibly impedes his opportunity to steal bases. A single or a walk for Pastornicky can turn into a "double" roughly 77% of the time. Hitting in front of a singles hitters like Bourn is the best opportunity to drive in runs. Bat Pastornicky 9th. Have him steal. Bourn or Prado are the best bet to hit singles on the entire roster. More runs are scored.
Move Heyward up in the lineup. So far this year he's hitting Line drives at a 25% clip and hitting more fly balls than ever before. His Isolated power is nearly identical to 2010 and so is his OPS. So far in this young season, his numbers look very close to 2010 by trading a slight amount of BB% for more hits. I expect his BABIP to go down to more sustainable numbers, but for his BB% to creep up to double digits like in 2010 and 2011. Essentially, his retooled swing and veteran-like plate approach means he is in his 2010 form (when he lead a playoff team in WAR and WPA). This is a guy who was rated the number one overall prospect in baseball, and hit a homer on his first MLB swing, and then finished 4th in OBP in the NL as a 20 year old. That's the guy who's batting 7th. Change that.
Don't use Chad Durbin ever again (unless the score is beyond 10 runs either way.)
Use Cory Gearrin and minimize his use against lefties as much as possible. Like Pastornicky, put a young player in the best opportunity to succeed. This is a talented player who hasn't allowed a run this year in AAA and has a career minor league ERA below 3. In 2011, you put a side-arming righty to face lefties in 42% of plate appearances. This is an inexcusable approach. In limited duty in the bigs he put up a 2.59 FIP last year. That's very good. But since lefties have such a good look at his delivery he had an ERA that ballooned over 7 due to an unexpected amount of hits. Still, in the majors his OPS against righties was .427! 1.157 against lefties! Holy crap! This is a guy who can be put in a high leverage situations against major league righties right now. He should see some 7th inning frames if the lineup begins with right handers. Now that he's back in the bigs, use him in a way that makes him better and makes the team better.
Throw away the rigid bullpen use. Don't be afraid to use Kimbrel in a tie game on the road without a lead. He's the best pitcher on the team. Don't manage just to curtail a statistic that was invented in the late sixties. Manage to get the most wins as possible. That may mean putting your best pitcher in a tie during the 9th, or even (gasp) in the 8th. Rigid bullpen use with pre-defined rules make little sense. There is a multitude of talented arms in the pen: O'Ventbrel, Medlen, Gearrin, Martinez. This is probably the best bullpen in baseball and it means you can alternate arms to avoid overuse. That means letting guys share roles. Each of those guys are more than capable of high leverage situations. You can use Martinez to pitch the 9th if you're up by 3 against the Mets. He probably nails down the save 95% of the time. Kimbrel probably nails that down 97% of the time. Is it worth it the run Kimbrel out there for every 3 run save if 95% isn't good enough? Of course not. Medlen is actually more effective against lefties than righties. Don't forget that. In an uninspiring trend so far this season, you have been timid about using O'Ventbrel without a lead. If the score is within one run either ways those are the guys most suitable for high leverage innings. It's almost as if you worry about only making the safe moves that can be sprung off like teflon in a post game conference - "I want to wait to use Kimbrel for a save." Sure, the press will leave you alone after that one line, but you're making the team worse if you don't use the best players in the most important situations.
Lastly, Be open to defensive shifts. Excellent defensive teams like the Rays have shown the benefits from infield shifts. The more intriguing move has been the infield shifts from mediocre defensive teams like the Brewers. Last year they shifted as much as anybody. With an infield of less than sure-handed guys like Fielder, Weeks, Beatancourt, and Hart, they improved their Defensive Efficiency, Defensive Runs Saved, and UZR to such a degree, it was astounding. A Mediocre group of defensive infielders like Chipper, Pastornicky, Uggla, and Freeman could really benefit from shifting against power hitting lefties. With sinker pitchers like Hudson, Venters, and Gearrin, the results are likely to be even more beneficial. The outfield defense is incredibly sound, but I remember Bobby Cox would occasionally shift Andruw to the left a little bit to utilize his range to help the left fielder. Bourn and Heyward could probably cover more ground than they are currently.
Essentially, Look for extra advantages. The team could be better if some simple moves took place.
Some Guy On The Internet