HOUSTON -- The only good thing that Eduardo Rodriguez can say about May is that it is over.

When the month started, the lefty was the unquestioned ace of the staff. Now, he is having the toughest time of anyone in the rotation.

With Rodriguez struggling again (4 2/3 innings, seven hits, six earned runs), the Red Sox were routed, 11-2, in the opener of a four-game series against the Astros at Minute Maid Park on Monday.

Rodriguez is tired of missing with his location.

“I make a lot of mistakes -- that’s why they got base hits and everything like that,” Rodriguez said. “Like I said on the last start, every time you make a mistake, that’s going to happen. That’s what happened today.”

The performance by Rodriguez raised more concerns about why he is having such a difficult time and how he will fix it.

For the Red Sox, May was bookended with E-Rod starts, as he pitched the first and last games of the month. In all, he made six starts, going 1-4 with a 7.28 ERA.

“It’s been a grind the last couple of starts,” said Rodriguez. “Have to go to the bullpen and work and get ready for the [next] one. It is what it is.”

After going 4-0 with a 3.52 ERA in April, Rodriguez’s season stats are currently not pretty (5-4, 5.64 ERA).

However, he has been down this road before. Take, for example, 2019, which is his best season (19-6, 3.81 ERA, 213 K’s) to date. In his first 10 starts that year, Rodriguez was 5-3 with a 5.43 ERA. In other words, pretty similar to what his stats are through 10 starts in ’21.

“It’s 30 starts, he’ll get 30 starts,” said Red Sox manager Alex Cora. “He’s healthy. You saw the stuff. He maintained his stuff throughout the outing. He just has to keep working, keep getting better. He did that in ‘19 when he was on top of the world, and he’s doing that right now.”

• Cora on return to Houston

Of the 97 pitches Rodriguez threw, the Astros swung at 39 and whiffed at just six. Of the 37 starts in which Rodriguez made 90 pitches or more since the start of the 2019 season, this was just the third time he had so few whiffs.

Is Rodriguez still shaking off the rust due to not pitching last season? Or is he still building back arm strength?

It’s plausible it could be both.

However, Rodriguez was in no mood to make excuses.

“I don’t think this has anything to do with missing last year, man. It’s just about location right now,” said Rodriguez. “I have 10 starts already in the season. I’m not going to blame that [on missing] last year. That’s something that I’ve just got to go to the bullpen and work on.

“I can’t blame any more that, ‘Oh, I missed last year.’ No. That can’t happen anymore. It’s just part of the process of going out there every five days. You’ve got to figure out a way to go on to the next one and have a good result.”

The next one is going to be a big one -- Saturday night at Yankee Stadium.

Cora is of the belief that things aren’t as bad as they seem with Rodriguez right now. In the late innings of Monday’s loss, he tried to convey that to him.

“I told him that if he throws the ball the way he threw it today, with one more adjustment, we’re in a good place,” said Cora. “I honestly feel like stuff-wise, the cutter -- that’s the one we were looking for. We still don’t have the sinker where we want it, but the four-seamer was good. There were some swings and misses, so as far as stuff compared to the last four or five [starts], even early in the season, his fastball and his cutter were the best.”

What is the missing ingredient?

“I think the changeup,” Cora said. “If we get the changeup where it usually is, we should be fine.”

It is understandable that Rodriguez wasn’t quite ready to see those silver linings after giving up a six-spot.

“I mean, I don’t feel like that about the result today,” Rodriguez said. “At least my fastball is getting there. The results say I gave up six runs, and that’s what it is.”

Whatever the issues are, fixing them will be vital for the Red Sox if they want to stay near the top of the American League East standings. Monday’s defeat dropped the Sox two games back of the white-hot Rays, marking Boston’s biggest deficit since the fourth game of the season.

Here is the best news of all for Rodriguez. The next time he takes the ball, it will be June instead of May.