Only two National League relievers pitched more innings than Cody Martin before Monday, but the Braves rookie insisted fatigue hasn’t been a factor in his recent struggles.

After posting a 1.54 ERA and .220 opponents’ average in his first 10 appearances, Martin has a 7.71 ERA and .370 opponents’ average in his past six outings. That included consecutive weekend losses at Washington, where he got both decisions and gave up three runs and two hits in each game after the Braves had rallied to tie or take the lead.

He gave up a two-run walkoff homer to blistering-hot Bryce Harper Saturday, and on Sunday Martin gave up a leadoff single to Ian Desmond and walked Jayson Werth to start the eighth inning. One out later, the Nationals got consecutive RBI hits.

“I feel good,” Martin said before Monday’s series opener at Cincinnati. “Just not (throwing strikes) consistently. I mean, they’re taking pitches all the way, they don’t even have to think about it. It keeps them comfortable when I do throw them over the plate.”

So he’s not tired?

“No,” Martin said. “In baseball you’re going to have ups and downs. I got off to a really good start, obviously, which I’m sure nobody thought would happen. I got the opportunity to pitch in some tight games there and things didn’t go my way.”

He was thrust into the eighth and ninth innings of tied or one-run games because closer Jason Grilli was dealing with back spasms, and setup man Jim Johnson was held back in case of save situations.

Grilli felt better Monday and was expected to be available for the series opener against the Reds. Manager Fredi Gonzalez planned to rest rookies Martin and Cunniff, who pitched in all three games at Washington.

Cunniff’s .059 opponents’ average was tied with Yankees standout Andrew Miller for the majors lead before Monday, and even with seven walks in 13 appearances his .211 opponents’ OBP was still more than 100 points lower than any other Braves reliever who’d pitched in more than three games.

The Braves’ lack of bullpen depth has been exposed in recent weeks, but without Grilli this weekend it was all the more glaring.

“It exposes (lack of depth),” Gonzalez said. “And we always talk about putting guys in situations where they’re going to be most successful. It’s a great learning thing for them, it really is. Because a week from now, 10 days from now, we may be back in that same situation. I hope (Martin) takes the positive — experiencing those emotions that happen in the eighth inning in a tie game — and learns from that.”