The main issue with Wren's draft is they were very top heavy, often producing only 1 or 2 guys that became legit prospects. The argument against that is, the hit rate on those top prospects was insanely high as Kimbrell, Minor, Simmons, Gattis, and Wood all became above average big league players. They also, produced a few role player guys like Ahmed, La Stella, and Drury (and apparently Sims now)
Coppy ended up a disaster as GM, and not simply because of his breaking of the rules. He made some pretty bad trades (Simmons, Kimbrell, Olivera). However, his drafts were pretty friggin good, both in producing actual major league contributors and quality prospect depth that can be used in trades or to supplement the major league team. We see at least 4-5 prospects from each of his 3 drafts that have become legit prospects or major league contributors.
Wren came into a pretty fortunate situation with a solid MLB team and a good farm (though not quite as good as it was before JS traded away 5 of best prospects for Tex). Unfortunately, Wren managed to trade away even more of that prospect depth and couldn't adequately replenish it. Combine that with some pretty terrible contracts handed out, and you have the reasons why he was fired.
I want to address the bold point first.
That's not true. While the 2007 draft would produce Heyward and Freeman, the top prospects from that year are kind of meh.
1 Was Schafer, somewhat of an upside but hardly a supreme talent.
2 was Heyward, great prospect, but by this point he had 48 Plate Appearances and was already number 2.
3. Jair Jurrjens - Wren acquired via trade
4. Brandon Jones
5. Gorkys Hernandez - Wren acquired via trade
6. Brent Lillibridge
7. Rohrbough
8. Locke
9. Hanson
10. Julio
While the bottom has talent, Keep in mind going into 2008 Jeff Locke had not pitched above ROokie Ball, Hanson was just starting to break though, and Julio was 17 and never pitched in the majors. That's not a top prospect list. 2 of them were just drafted/signed and hadn't played much if at all. 2 of them we acquired by Wren. That's not a good farm. If he still had Feliz, Salty, Andrus and Harrison (aka the top 4 prospects in 2007) and it's not like the 2008 braves were filled with kids, of quality players under 28, the braves pickins were thin, McCann, Johnson, Teixeira, Escobar, Prado, Jurrjens, and that's about that. Yes there were lots of people we were sold as being great like Francoeur, Boyer, Parr and Blanco, but honestly they're all meh for the most part. Morton wound up being quite good recently, but that has no effect on the BRaves as they didn't value him.
Wren won so many trades it wasn't funny. The onyl ones you'd argue he lost were Teixeira and Escobar. Both by many reports the negative aspects were forced by old guard. As the rumor was the BRaves wanted a MLB first baseman back in the Teixeira trade. But to me both of these trades still fall on the failure of the first Tex trade. If that trade doesn't happen, Escobar is dealt when his value is high and not for another Short Stop because Andrus would take over as our starting Short Stop. Salty and McCann would likely form a 1B/C platoon until Freeman was ready. Feliz would have made our bullpen one of the best in baseball in the 2010s, and Matt Harrison was a solid starter.
Anyway, that's my rant about that weird myth that the Braves farm was fine when Wren took over.
And it wasn't Wren that traded away that depth. It was JS, in 2007 he let go Davies, Ledezma, and Startup as well. They also traded Marte and Max Ramirez in 2006. Which I'm not against any of those trades. But JS was basically taking AAAA guys and turning them into MLB players, which is fine, but that's why our depth was diminished.
Wren was a master of trading MLB pieces, Adam LaRoche was acquired back from Kotchman, McLouth trade utilized some AAAA prospects, Melky, Viz and Dunn were acquired for Vazquez, Dunn and Infante were used for Uggla, Michael Bourn trade involved some depth trading, but by then the minors were mostly restocked, the lone big prospect trade he made was the Upton trade. but honestly that still held a lot of the trade Value in a major league player (Prado) Wren was a master of trades and his trades almost all made the Braves better, except the 2 I pointed out above.
Contracts were a bit of a problem, but none of them were panned at the time. Everyone thought the Uggla contract was a Bargain. Everyone thought the Upton contract was fair. The reason the Upton contract is looked back negatively was because the CF market shifted from what was expected. Everyone expected the Twins to trade SPan or Revere, not both and that shook the market up. Of course patience would have paid off, but Patience ****ed the BRaves in the Lowe signing where they were working on a number of other deals then Lowe basically said he would only sign for the Braves over the Mets if we gave him more money. And it's not like the Braves were immune to bad contracts in the past.
And no trade Wren made is anywhere near as bad as either Olivera trade.
Coppy drafted and signed well, but his trades except for the Heyward train were nothing to write home about. Sure we did well, but when you're trading Heyward, Simmons, Kimbrel, Gattis, and Justin Upton you should be getting back talent. It's only a fool that cannot get back talent for that level of talent and Coppy wasn't handcuffed with "we need an MLB ready player" on almost any of those trades as it was a clear rebuild. He wasn't a bad GM aside from cheating and being banned from baseball, but he wasn't a wunderkind either. He was a good GM who made a couple of great moves but ultimately will be defined as the guy who traded for all the pitchers who already had Tommy John Surgery. A risky move which has paid off for some and not for others.