OAKLAND -- The Angels had momentum on their side heading into their three-game series against the first-place A’s, having won six in a row and posting a 9-2 record in June that propelled them one game over .500 for the first time since May 1.

But right-hander Dylan Bundy's season-long struggles continued as he allowed seven runs in just 2 1/3 innings in an 8-5 loss to the A's in the series opener at the Coliseum on Monday. Bundy, who was the club’s Opening Day starter, fell to 1-7 with a 6.98 ERA.

"Early this season, I referred to him as an ace often because that's what I'd seen with him," Angels manager Joe Maddon said. "And I don't know the answer. I just think things are off and the ball is not coming out as crisply as it has in the past. It's just different. It's a different Dylan watching him out there because he's just not as sharp or quick."

It’s been a particularly ugly stretch for Bundy since May 2, as he’s posted a 9.82 ERA over his last seven starts. He was coming off his best outing during that stretch, allowing two runs over 5 2/3 innings in a win over the Royals last Monday, but he failed to build on it and ran into familiar troubles.

Bundy was staked to an early 1-0 lead on Juan Lagares’ first homer of the year in the second, but he gave it right back by surrendering a two-run blast to Sean Murphy in the bottom of the inning. It was the 14th homer he's allowed in 12 starts after serving up just five in 11 outings last year.

Bundy said he’s been leaving too many pitches over the middle of the plate this season and that it’s something he’s tried to correct in bullpen sessions.

"You're always working on it, I mean, I've been throwing two or three bullpens between starts," Bundy said. "It's not a lack of work or a lack of reps. Just when it comes down to it, I'm throwing balls down the middle that shouldn't be going there. They should be on the edge or off the plate. I'm just not doing that right now."

The wheels fell off for Bundy in a five-run third that knocked him from the game and essentially put the game away for Oakland early. He allowed five of the first six batters he faced to reach and the lone out he induced was a sacrifice fly to right field from Matt Olson. He exited after allowing a two-run single to Mitch Moreland that went just under the glove of second baseman David Fletcher. Reliever James Hoyt came in and allowed an inherited runner to score on a two-out RBI single from Elvis Andrus.

Bundy's velocity was down a bit, as his fastball averaged 89.5 mph, compared to his season average of 91.4 mph. His spin rates were also noticeably down, though they were similar to his last start against the Royals.

"Body's healthy, I'm feeling fine," Bundy said. "I noticed it was a little bit down there. Wasn't worried about it. I just didn't have the same carry on the fastball tonight."

Bundy simply hasn’t looked like the pitcher he was last season, when he posted a 3.29 ERA and finished ninth in the balloting for the AL Cy Young Award. His rough year has also come with bad timing for him, as the 28-year-old is set to be a free agent after the season.

At this point, Bundy will need to turn it around just to remain in the rotation, especially with the emergence of lefty Patrick Sandoval, who has filled in capably in recent weeks with a 2.77 ERA in five starts. Fellow lefty José Quintana is set to start a rehab assignment soon and the Angels will have to decide who he will replace.

Bundy still has some time to turn it around, but Maddon was a bit concerned by his fastball velocity.

"The velocity was down and it was obvious," Maddon said. "I thought he had a really good curveball and some changes were pretty good. But I don't think his velocity played up to the point where the other pitches were as effective. It just seemed like they were on everything and there was nowhere for him to go. That's what I saw."