It’s no longer a first-half aberration.

At the time that Josh Beckett went onto the disabled list in mid-May, the confusion surrounding his season had little to do with his injury. Indeed, the Red Sox and the pitcher almost seemed relieved that he would have time to recalibrate.

Beckett had been off to a wildly inconsistent start to the season that had ultimately been disappointing. There were a couple of dominant outings, but by and large, the right-hander had been shelled to the tune of a 1-1 record and 7.29 ERA through eight starts preceding his back injury.

When he returned, it seemed as if the Opening Day starter had left behind his challenging start to the year. In his first three outings off the DL (against the Mariners, Angels and Indians), Beckett was 2-0 with a 2.18 ERA, and the Sox were heartened by the notion that he was trending back in the right direction.

Yet some of that optimism now seems to have been premature. On Thursday, he added to what is now a year of confusion and underperformance in his club’s 7-2 loss to the Angels. (Recap.)

Beckett was overpowering early, cruising through five shutout innings in which he allowed just two hits, successfully managing his delicate 1-0 lead. But then the wheels came off with striking suddenness, as the right-hander gave up four runs in a span of four batters in the sixth and was charged with another pair after leaving with one out in the seventh.

It was, to say the least, an uneven performance, a fact that the Sox acknowledged even as they tried to emphasize the positive aspects of it.

“I thought the first five innings, he was solid, crisp, good plane on his fastball, executed his pitches,” Sox manager Terry Francona said. “I know you’ve got to put it together for a whole game. … The hope is he can build off of the positive that he did and not let the sixth get in the way of the rest of the season.”

Both Francona and Beckett said that the pitcher was not injured. Yet that fact — backed up by the way the Angels struggled against him for most of his outing — only added to what has been a confounding season.

With his final line of 6 1/3 innings, seven hits and six runs (all earned), Beckett is now 0-2 with a 10.69 ERA in his last three outings. And with that, Beckett’s record since returning from the DL stands at 2-2 with a 5.89 ERA. Based on the numbers, he has been better than he was in the first half, but not by much.

Beckett did show good life on his pitches at times. His curveball, in particular, was at times a dirt-kissing swing-and-miss offering. He elicited nine swings and misses in the game (four on curves, three on cutters, two on fastballs) and he struck out six.

“Mostly, his fastball was down in the zone. He threw some curvevalls that he was able to finish hitters off with,” pitching coach John Farrell said. “I think that’s been one of the more encouraging signs is that in the six starts that he’s had since coming back, his curveball has shown more consistency, more of a true weapon that we’ve seen from him.”

Of course, these positives are of great significance for the Red Sox, not just for this season but for the next four, during which he will be paid (per the terms of his four-year, $68 million deal) as one of the game’s elite starters. And so, as baffling as Beckett’s struggles have been in 2010, the idea that he is not far from the form he showed prior to this year with the Sox is significant.

Toward that end, the Sox do have some legitimate cause for hope. Beckett is striking out 8.3 batters per nine innings in six starts since his return, close to the 8.7 punchouts per nine innings he’d produced from 2007-09. He is likewise walking 2.2 batters per nine innings in those six starts, just slightly off his pace of 2.0 per nine frames in the past three seasons.

“He’s been more powerful,” Farrell said of Beckett’s post-injury performance as compared to his early-season efforts.

Yet he has still been vulnerable, particularly in his recent starts, particularly on his fastball.

It was noteworthy that all seven hits that Beckett allowed came on 92-94 mph fastballs (one was on a cutter). For the right-hander this year, his mistakes on off-speed pitches have resulted in balls. His mistakes on fastballs have often resulted in hits.

Certainly, that was the case on Thursday. But Beckett did not think that it was the type of pitch so much as its location that led him to harm.

“If you throw balls in the middle of the plate, you’re not going to get swings and misses,” Beckett said. “You might get a foul ball occasionally, but you’re not going to get a swing and miss in the middle of the plate.”

The Sox’ problems on Thursday ran deeper than Beckett. The team’s offense appeared to be reliant solely on David Ortiz and Adrian Beltre for production, and the late scratch of Dustin Pedroia offered a reminder that it would be unfair to expect the same impact from him after his broken foot as he delivered before it.

Nonetheless, the ongoing inconsistencies of Beckett loomed larger than those concerns. The Sox have maintained throughout their rash of injuries that their starting pitching is capable of keeping them in contention. But with Beckett failing to offer the team solidity to this point, that blueprint is in jeopardy.