Instead, they've performed more like aces.
Santana looks to pick up where Harang left off in an impressive series-opening start as the Braves go for a seventh win in eight tries Saturday night.
Atlanta (11-5) is without Brandon Beachy and Kris Medlen for the season due to elbow surgery, while Mike Minor is trying to come back from tendinitis in his left shoulder.
With the hopes of softening the blow of those absences, the Braves signed Santana (1-0, 0.64 ERA) and Harang to one-year contracts.
They're doing much more than that. Harang's 0.70 ERA is only bested by Santana's for the lowest by an Atlanta starter.
Harang turned in another outstanding performance in a 6-0 victory Friday. He tossed seven no-hit innings before exiting after 121 pitches, but Luis Avilan gave up a single to David Wright in the eighth.
"I want him pitching 27 more times," manager Fredi Gonzalez said. "If it was the ninth inning, maybe, think about (keeping him in)."
Now, Gonzalez will give the ball to Santana, who has won both of his career starts against New York (8-8) behind a 0.64 ERA. He was superb in the latest matchup April 9, yielding three hits through eight scoreless innings of a 4-3 win.
The right-hander's latest outing for the Braves was also impressive in Monday's 9-6 win at Philadelphia. He matched his career high of 11 strikeouts while allowing the only run on a solo homer in six innings.
"I've been so impressed with him," Gonzalez said. "He's got command, he's got some life, he knows how to pitch."
Gonzalez may also be impressed with the Braves' bats, which have produced a .280 average with 14 homers and 39 runs while Atlanta has won six of seven. They pounded out 12 hits with five doubles and a two-run homer by Freddie Freeman in the series opener.
Freeman is among baseball's leaders with a .390 average, while his five homers and 12 RBIs are tops for Atlanta. He's also hitting .429 with four homers and 13 RBIs over the past 10 meetings with the Mets.
Bartolo Colon (1-2, 6.00) is seeking some consistency for New York, and facing Atlanta could help.
Colon has a 1.20 ERA while winning all four starts against the Braves, including a 4-0 road victory April 8 during which he allowed six hits in seven crisp innings.
The right-hander followed that by surrendering nine runs and 11 hits - four homers - in five innings of a 14-2 defeat to the Los Angeles Angels.
Colon, though, was reportedly troubled by an aching back that could force him out of Saturday's scheduled start.
If Colon can't go, the Mets would then turn to Daisuke Matsuzaka, who was recalled from Triple-A Las Vegas on Friday.
"If Bartolo's back stiffens up on him, (Matsuzaka) has got to be ready," manager Terry Collins told the team's official website. "He'll come as if he's going to pitch ... we've got to have a backup plan, and right now Daisuke is our best option."
Matsuzaka went 3-3 with a 4.42 ERA in seven starts with the Mets last year, and that includes allowing six runs in three innings of a 13-5 loss at Atlanta on Sept. 2. The right-hander had a 2.25 ERA in two starts with Las Vegas.
He had a hard time with Freeman on Sept. 2, surrendering a two-run double and a three-run homer.