Shortstop Andrelton Simmons led the National League with 25 defensive runs saved in 2015.

Brad Penner USA TODAY Sports

Andrelton Simmons is on his way to Los Angeles.

The Atlanta Braves traded their 26-year-old star shortstop, the two-time National League Gold Glove winner and arguably the top defensive player in baseball, to the Los Angeles Angels for two highly rated prospects, veteran shortstop Erick Aybar and cash, according to multiple reports. Braves catching prospect Jose Briceno was also reportedly thrown into the deal.

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The trade was first reported by MLB.com reporter Jesse Sanchez.

The prospects included in the deal are Sean Newcomb and Chris Ellis, two highly regarded arms in the Angels organization. Both former college arms pitched at the Double-A level last season and were considered the top two prospects in the Angels organization.

Newcomb, in particular, is the standout prospect in the deal. The 6-foot-5 left-hander rocketed up through the Angels system in 2015, posting a sub-3.00 ERA at every stop. The former 15th overall draft pick has drawn comparisons to Jon Lester and adds a rare southpaw to Atlanta's overflowing surplus of high-ceiling arms in the farm system. Ellis, a third-round pick in the 2014 draft, is a 6-foot-4 right-hander who posted a 3.92 ERA in Double-A last season.

Trading Simmons, one of the organization's last remaining pieces of a promising young corps along with first baseman Freddie Freeman and starter Julio Teheran, was never going to be simple. He's a fan favorite and perhaps the greatest defensive player of his generation at a premium position on a team-friendly deal.

Simmons was signed through the 2020 season, and while the contract escalates over time he was still a bargain given his season-by-season value.

The rebuilding move appears to be a clear indicator that new general manager John Coppolella and Atlanta's front office had concerns over Simmons' offense. While the glove provided more than enough value, the former second-round pick has hit below league average for three straight seasons -- and for a team that ranks dead last in runs scored over the past two years, that's hurt.

Simmons' departure will not leave a gaping hole to be filled by the Braves' farm system thanks to Aybar, the veteran shortstop entering the final season of his contract. In terms of value, Simmons and Aybar have lined up over the past two seasons -- both have posted a 5.2 WAR over that span -- and if Aybar hits near his career averages he could provide an offensive upgrade for the 2016 team. Aybar's contract is worth $8.5 million next season.

The inclusion of Aybar in the deal also buys the franchise one more year as it waits on top prospect Ozhaino Albies to develop in the minors.

Trading young stars is difficult -- and risky. If Simmons ever figures things out at the plate, he could become one of the most valuable players in baseball. That's the risk the Braves took on Thursday. Still, with two more promising arms in Newcomb and Ellis and a placeholder at short, Atlanta continues to compile assets for the future.