Bell posted a 2.70 ERA over his first 15 appearances this season, though his hits-to-innings-pitched and his strikeouts-to-innings-pitched ratios weren't quite as good as they were during the 2007 season, when he was one of the top relievers in baseball.
It took Bell a little longer to refine his mechanics this season after he developed three knots on his right triceps in Spring Training, which adversely affected his mechanics.
That also caused Bell's velocity to drop, as his fastball was often in the low 90s and not the usual mid 90s.
"Coming into Spring Training, I didn't let on that I had the three knots, I just kind of played through it," said Bell, who also pointed to factors such as the layoff from the China trip in March and getting sick when he returned.
"I don't think it was just one thing ... but my mechanics weren't always on target," Bell said.
They are now, as Bell has a 1.56 ERA since May 1, with 22 strikeouts in 23 innings. Bell has allowed 13 hits in those 23 innings.
"I'm really starting to feel comfortable with my mechanics, and everything is clicking," said Bell, who had a 2.02 ERA in 81 games last season. "Every time I throw a ball, my mechanics are 99 percent right on target. ... I feel I can give everything I have.
"That's where the [improved] velocity comes in. It helps because the curveball is a little tighter, the fastball is a little sharper and the sink is a little better. About the start of May, it started clicking, feeling normal again."
San Diego manager Bud Black has noticed.
"The last month or so, you've seen Heath in the same light that he pitched most of last year," said Black.
"Early in the year, his velocity wasn't where it was last year," Black added. "He kept saying his arm was fine. He's regained that form where his mechanics are more consistent. But no doubt, he's throwing the ball great."
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.