SAN FRANCISCO -- The most intriguing team in the Giants' farm system is now the one that plays in Virginia.

The Giants will promote top prospects Joey Bart, Heliot Ramos and Sean Hjelle to Double-A Richmond, a source told NBC Sports Bay Area. The Richmond Flying Squirrels confirmed the roster moves later Thursday afternoon. They will join current Flying Squirrel Logan Webb as an exciting group moving through the system together, and all four are now in position to get a look in the big leagues next year.

Bart, Ramos and Hjelle are three of the organization's top six prospects, per MLB Pipeline, and all have excelled in their first season of A-ball.

Bart, 22, is the organization's top prospect, the second overall pick a year ago and one of the best catching prospects in the minors. He was briefly sidelined by a hand injury earlier this year but has a .793 OPS in his first full season with 12 homers in 234 at-bats. Bart is advanced defensively and could make a push to be Buster Posey's partner as early as next spring.

Ramos is just 19 but the Giants hoped to accelerate his development, and he responded to the challenge of facing High-A pitchers. The outfielder hit .306 in the California League with a .885 OPS and 13 homers in 294 at-bats, showing improved plate discipline in his second full season. The Giants planned to have Ramos a bit behind Bart, but he was San Jose's best hitter and now will take his shot at the much tougher Eastern League. There's not much ahead of Ramos on the depth chart in Triple-A, and he has put himself in the discussion for a 2020 promotion to the big leagues.

For Hjelle, this is already the second promotion of the season. The 6-foot-11 right-hander had a 2.66 ERA for Augusta and followed that up with a 2.78 ERA in the hitter-friendly California League. The 22-year-old struck out 74 batters and gave up just two homers in 77 2/3 innings.

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Hjelle joins Webb, also 22, in the Flying Squirrels rotation. They are the two best pitching prospects in the organization and should both get extended looks next spring.

The Ramos promotion was first reported by freelance writer Marc Delucchi. The San Francisco Chronicle was first with the Bart and Hjelle news.