Rick Porcello was absolutely dominant throughout April, as the Boston Red Sox right-hander went 4-0 with a 2.23 ERA in six starts.

But the 2016 American League Cy Young Award winner has struggled so far in May, going 1-1 with a 5.71 ERA in three starts, the latest of which came in a 6-5 loss to the Oakland Athletics on Monday at Fenway Park.

Porcello gave up five runs on nine hits (two home runs) while striking out five in six innings against the A’s. The righty has given up 10 earned runs over his last two starts, as much as he gave up in his previous six starts combined.

The right-hander attributed his trouble’s Monday to the inability to capitalize when he needed to during the A’s three-run fourth inning when catcher Jonathan Lucroy ripped a two-out, two-run double to left to give the A’s a 3-2 lead and Dustin Fowler followed with an RBI triple to make it 4-2.

“Three innings, they scored one run so I kind of disagree with that, I don’t think there was a whole lot trouble early,” Porcello said, as seen on NESN’s Red Sox postgame coverage. “Ground ball through the hole in the second and ground ball to third, they got runners on like that, but we can live with those. The fourth inning was the biggest inning, you know, two outs, have an opportunity to get out of it, give up the big hit, big double to (Jonathan) Lucroy and then nine hitter comes up. Actually, both those pitches felt like were halfway decent pitches, just put good swings on them and nine hitter hit a ball to center off the wall and scored another run.

“The fourth inning, the pitches with two outs to Lucroy and Fowler were to me the biggest pitches of the night and they capitalized and I didn’t.”

Porcello noted he believes Monday’s outing came down to the A’s putting good swings on some good pitches and his inability to execute when he needed to, but he felt his stuff overall was good and doesn’t feel there is any reason to be concerned.

Here are more notes from Red Sox-Athletics:
— Blake Swihart got the start Monday at designated hitter. The 26-year-old went 0-for-4 but hit an absolute missile in the eighth inning that was caught by right fielder Mark Canha. The ball left Swihart’s bat at a staggering 108.1 mph, and more times than not it falls for a hit.

— Tyler Thornburg pitched in a rehab outing for Triple-A Pawtucket and didn’t have his best stuff. The right-hander retired only one of the four batters he faced, giving up a single, a walk and a home run. He only threw eight of 19 pitches for strikes, per Alex Speier of The Boston Globe.

— J.D. Martinez hit his 11th home run of the season Monday. He is hitting .405 with seven home runs since April 25.

— Dustin Pedroia went 1-for-3 and played five innings in the field during a rehab stint for Triple-A Pawtucket. The Red Sox second baseman has been working his way back from offseason cartilage restoration surgery and he said he felt good after his first game for the PawSox, per Steve Hewitt of The Boston Herald.

— The Red Sox still are the only team that does not have a pinch-hit. They now are 0-for-16 after Mitch Moreland’s ninth-inning fly out Monday.

Thumbnail photo via Brian Fluharty/USA TODAY Sports Images