When the Braves traded slugger Evan Gattis to Houston for prospects Wednesday, president of baseball operations John Hart knew there would be more howling from critics. Similar to when he traded Justin Upton for prospects last month, but perhaps more so, since Gattis was not a pending free agent and was homegrown like Jason Heyward, who was traded in November for a young pitcher and a prospect.

It’s been that kind of offseason for Hart and the Braves, who’ve transformed one of baseball’s five worst-rated minor league systems into one of its top 10 by going on a trading frenzy that’s brought back a bevy of prospects, including eight pitchers. They did so at considerable cost. They traded half of last year’s lineup, including three of the team’s top four hitters, while adding but one proven lineup regular, free agent Nick Markakis.

Their main objective was to rebuild a farm system that had become alarmingly thin under fired general manager Frank Wren. The Braves aimed for building the foundation for a serious contender in 2017 in their first season in a new ballpark, while remaining respectable and hopefully competitive until then. Hart and Co. believe they’ve done that.

“In looking at this (Gattis trade), I think we’ve added to the group we’ve been working on this winter,” Hart said, referring to three prospects he got from the Astros, led by Michael Foltynewicz, a potential future ace, and third baseman Rio Ruiz. “It just creates a lot of options when you have the young players we’ve added to the system. It creates a ton of options as you go forward. And we certainly aren’t through with the major league club.

“We knew this was a club that was offensively challenged last year. We have a nice core coming back. It’s going to be a different type of offensive club this year, but I still like the club we have. It’s going to be a fun club to watch.”

The Braves also traded away much of a strong bullpen, including Jordan Walden, David Carpenter and Anthony Varvaro. But they didn’t trade All-Star closer Craig Kimbrel, and have rebuilt his supporting cast by signing several free-agent relievers, including former closers Jason Grilli and Jim Johnson, and trading for Arodys Vizcaino.

The starting rotation, despite losing free agents Ervin Santana and Aaron Harang, should be solid again after Shelby Miller was acquired from the Cardinals in the Heyward trade and several fifth-starter candidates were signed or accumulated through other deals.

It’s the offense that seriously concerns fans. The only frontline addition, Markakis, had neck surgery after signing a four-year, $44 million contract. He’s expected to be recovered before spring training, but the lineup looks less than formidable after Freddie Freeman and Markakis.

Right now the Braves aren’t sure who’ll be in left field, where Justin Upton played last year and Gattis had been penciled in for a move from catcher.

Then again, as Hart has pointed out a few times, it’s not as if he broke up the ’27 Yankees. Last year’s Braves scored the second-fewest runs in the major leagues and were far more proficient at striking out than producing sacrifice flies, home runs, or hits with runners in scoring position.

“It’s not like we abandoned the club (for 2015),” Hart said. “We still obviously have some things that we are going to look at. Look, this is a club that’s going to have to be an underdog. It was going to be an underdog whether we traded Gattis or we didn’t. I mean, we still weren’t going to be picked to finish first.

“It will be a different club. I’m sure there will be a lot of questions and, ‘Boy, the Braves have run up the white flag.’ That’s not the case. We’ve added a Markakis in the mix and we’ve got some maybe different-type makeup guys around the club. I think it’s going to be a fun club to watch play, quite frankly. Is it perfect? No. Are we finished with it? No.”

The Braves are believed to have at least $12 million available and could sign one of the remaining free agent outfielders, such as Nori Aoki. Hart also mentioned the possibility of a platoon that would include switch-hitting Zoilo Almonte, a former Yankee who signed as a free agent and had a fine winter-ball season in the Dominican Republic.

Hart didn’t say who else might be in such a platoon. Possibly someone they acquire in the coming weeks, or Cuban free-agent signee Dian Toscano, provided Toscano’s paperwork finally gets done and he makes it to spring training.