Justin Verlander knows what’s wrong with Justin Verlander.

“Tinkering,” he told me, “is what I would call it.”

Of course. Tinkering.

In his last three starts, Verlander has allowed 16 earned runs over 12-2/3 innings. Fans, scouts and opposing hitters would choose a different participle: Struggling. But Verlander didn’t use that S-word once during a 15-minute conversation Friday — an indication the bizarre May has done little to change his swashbuckling psyche.

Verlander has been the American League’s best starter over the last four-plus seasons. He has the MVP and Cy Young hardware. So great is his talent and swagger that, when on the mound, Verlander regards baserunners as flukes. Hits and walks are against the natural order.

Lately, those offensive accidents have become more numerous. He has a 7.32 ERA in four starts this month.

For this, Verlander offers an explanation I don’t suspect you’d hear from other pitchers: At the end of April, he was 3-2 with a 1.83 ERA. And he decided it was time to make changes.

“I think I had the best April of my career, but I’m always a perfectionist,” the Tigers ace said. “I wanted to be better. So I started tinkering, and I feel like it had the opposite effect.

“I can’t fault myself for getting worse because I tried to get better. It didn’t work, so go back to basics and get to where I need to be. Thankfully, I’m somebody who makes adjustments really quickly. I feel like that could have caused a slump there, too. Because I make adjustments so quickly, I’m able to work on lots of different things at once. That threw me off a little bit.”

Got all that?

Because a 1.83 ERA wasn’t good enough for Verlander, he took his delivery to the pitching mechanic . . . and came back with a 3.66 entering Monday’s start against Pittsburgh.

We sportswriters have Control-Z to save us when our best-intentioned efforts must be undone. Pitchers aren’t so lucky. Tweaking the tweaks — against world-class competition, in front of 40,000 people — is an arduous, frustrating task.

Verlander admits that he undertook the project partially because of his widely-discussed drop in velocity at the beginning of this season. He’s not completely sure why his fastball was off by two or three miles per hour, particularly in his earliest starts.

But he has theories.

“I feel like it had a lot to do with being three weeks behind in spring,” Verlander said of his delayed throwing program because of the 266-2/3 innings he threw last year. “The workload (in 2012) might have had something to do with it. The cold weather might have had something to do with it. It might have been all of the above.