PHOENIX -- It has not been a fun 10 days or so for Madison Bumgarner.

The D-backs left-hander has been battling some type of cold/flu which has sapped him of energy and strength and has led to him leaving his past two starts sooner than he would have liked.

On Sunday, Bumgarner left after allowing the Mets just one unearned run over five innings, gassed after 78 pitches. In his start before that against the Nationals in Washington, he made it through five with two unearned runs.

"We've been dealing with some stuff, trying to get it knocked out," Bumgarner said. "But it has been … it's been a struggle. Hopefully we can get all that better and move on and get the [pitch count] built up. I'm not sure what it is. I know it's not COVID. We've tested 37 times for COVID, it's not that. So, I don't know, but it's lingering for sure."

The game went south for the D-backs after Bumgarner left the game, with the Mets scoring five times off the bullpen as they won 6-2 to capture two of three in the series.

D-backs manager Torey Lovullo was tempted to leave Bumgarner in the game Sunday, but after watching his ace, he knew that it was probably best to get him out.

"He did a great job through five innings," Lovullo said. "His pitch count was in an area where he probably had 10 to 12 pitches left. He felt a little gassed. He hasn't been feeling great but he went out there and did an unbelievable job with all things considered. I feel like I've gotten to know Bum pretty good and I can tell when he's at the end of his tank and I felt like he was in those last 20 pitches. I always appreciate the effort he gives. It's a never-ever-back-down mentality."

Bumgarner has carried a positive Spring Training into the regular season where after four starts, he has a 1.00 ERA.

Before each of his past two starts, though, Bumgarner wondered if his illness would impact his results, but so far it hasn't.

"They both could have been a wreck," Bumgarner said. "It's been pretty hard, but I still go out there and make pitches. It hasn't had an effect on my stuff all that much. I've been pretty happy with it."

One of the reasons the game fell apart after Bumgarner left was once again due to defensive struggles.

The D-backs committed three errors, but it was more than just that. There were several other plays that Lovullo thought they could have made.

"We just got to play full speed and trust it," Lovullo said. "Trust our hands, trust our eyes, trust our feet and make plays. It's simple. Simple demands. And these guys practice hard and they get after it. We just got to get after it in the game."

Having shortstop Nick Ahmed back in the lineup certainly helps the defense. The two-time Gold Glove winner, who was activated from the injured list Friday, made a pair of outstanding plays Sunday.

"We haven't played the way we're capable of or want to defensively," Ahmed said. "[There are] some plays that seem routine that need to be made but are not being made consistently enough. Obviously it happens occasionally where I miss balls, and nobody's perfect, but just overall as a whole, we got to make the routine play. It's something that we're not doing consistently enough. I wish I had a good answer for you as to why, but we're going to keep working on it."