PORT CHARLOTTE, Fla. -- Rick Porcello didn’t just wait to get healthy during the three-plus weeks he spent on the disabled list last August. Porcello had to teach his shoulder to work again.

Porcello endured one of the worst stretches in his career to open his stint with the Red Sox, one that saw him yield 20 home runs in 20 starts en route to a 5.81 ERA. What he later found to have contributed significantly to the problem was a release point that had drifted high enough that he wasn’t getting the movement he wanted from his signature sinker. A pitch that should dive down and away from lefties instead was running like a four-seam fastball -- and it was getting hit.

"I was really having a difficult time locating it," he said. "Everything seemed to be up and running, acting more like a running four-seamer than a sinker. I’d be starting them where I’d started the pitch my whole career, where it would sink down where I wanted it to, but last year I’d do that and it would get crushed."

Even more than throwing in the bullpen, something he’d been doing all along, what got Porcello back to the proper arm slot was work with the Red Sox training staff twice each day during his stint on the disabled list. Both before and during each game he spent on the shelf, the training staff put him through stretching and strengthening exercises to designed to break the bad habits he’d developed.

In his final eight starts of the season, all after he’d been activated, he posted a 3.14 ERA with 57 strikeouts in 57 1/3 innings pitched. He allowed just one home run in his final four starts.

Porcello endured an ugly start on Sunday afternoon against the Tampa Bay Rays, surrendering three doubles and a Hank Conger home run in three innings of work in a 13-5 defeat.

"I don't like the line, for sure," he said afterward. "I don't like going out there and giving up eight runs and 10 hits. But it's a work in progress. Clearly I'm not where I want to be yet, but it's getting there. It doesn't look like it, but I feel that I'm improving."

Three innings at Charlotte Sports Park in March matter less, the Red Sox hope, than the adjustments Porcello made in games that counted down the stretch last season.

Porcello had encountered similar trouble back in 2012 while with the Detroit Tigers. That season had seen him make the adjustment by midseason, and his ERA dropped with his arm slot -- from 5.18 in mid-June to 4.59 by the end of the season. But this adjustment took him longer to make.

Porcello and Red Sox pitching coach Carl Willis had identified a problem with his release point before the awful July 29 start that made some time away from the field a no-brainer. The problem for Porcello was that he couldn’t think about his mechanics while he was trying desperately to stay afloat.

"A lot of times it’s not so difficult to see," Willis said. "It’s just difficult to fix."

"I could manage it in the bullpens, and I could get my arm back to where I wanted it to," Porcello said. "But when I’d get into competition, in the moment, that’s not the first thing that’s on my mind. The first thing that’s on my mind is getting that guy out. Especially when I’d get into tough situations, I’m just thinking about scratching and clawing and giving us a chance to win. I’m not thinking about whether my arm is two inches too high or not."