For me it's about probabilities and strengths relative to weakness.
1. The Braves have a number of holes at the ML level line-up. And, even where the holes are "filled" the players that are there are either inadequate (Markakis, Flowers) for a good team or are at an age where they will be in decline (and expensive) by the time the Braves can realistically be good again (Freeman) or are of a type where there are multiple numbers and only one need e used (Mallex and Ender). So, essentially, thinking long term (not how can I make the 2017 better but how does the team become competitive and stay that way), essentially the entire line-up less 2B & SS (with Swanson and Albies penciled in there) and an OF position (with 1 of Ender or Mallex penciled in there) needs an infusion of talent - 1B more long term if you keep Freeman.
2. The Braves historically have been pretty bad at developing high quality ML hitters. Even the ones who roam the ML today (Heyward, Freeman, McCann, Francouer, etc.) are not as good as their talent suggests that they should be, although McCann comes closest over his career with Freeman being in there as well (I am talking offensive value). It just isn't something the Braves have been especially good at doing.
3. The current minor league prospects are mostly very far away (Riley, Acuna, Wilson) are or falling on their faces (Davidson, Ruiz) or appear to be marginal ML players (Peterson) with the exception of the aforementioned Albies and Swanson. So there isn't a lot of realistic help to even project to be available.
4. The FA crop is horrible for 2016-2017. The few bats that are good and available will also be old and expensive. Spend $30M per year over 4 years for Cespedes? Makes the lineup immediately better, but doesn't fill all the holes AND creates a cash flow and performance problem in 2019 & 2020 just when the majority of the young pitching will be mature. Sign Bautista? Even worse.
5. Trade for your offense? OK, what are you going to give up? What would Braun cost in terms of Braves prospects? The Brewers would want young pitching - MULTIPLE young pitchers. Let's say you get Braun for Newcomb, Soroka and Minter. Aren't you undoing what you just worked so hard to do?
6. The Braves have worked hard to trade for and draft a large number of pitching PROSPECTS. It is true that they are just prospects BUT your scouts and baseball people tell you these guys are good and will form your rotation of the future. But, it takes quantity to produce a few of quality.
7. Teheran is a good young starter who is signed to a reasonable contract, who has no significant injury history and appears to be a reasonable bet to produce value through the term of his existing contract. He's a very good #2 but doesn't appear to have the stuff or the steadiness to be a #1. Since Stras re-signed with the Gnats and since the FA and trade market is so bare, he is likely the most VALUABLE pitching trade piece in baseball which means that you can bring back multiple pieces to fill a number of those lineup holes. Is there a chance that he won't be adequately replaced from within by the young pitching on hand with the Braves? Of course. It's a bit of a gamble that the work done up to this point has been done well. However, it is less of a gamble than standing pat and hope for miracles to spring from the minor league system as is to fill current and near future holes in the ML lineup.
