BRADENTON, Fla. -- If you can never have too much pitching, as the saying goes, you definitely can't go wrong if much of that pitching is left-handed. Southpaws are the gold standard of baseball. And so it is that the Pirates have assembled a deep roster of candidates to complement Wandy Rodriguez as a second lefty in their rotation.

There's Jeff Locke, who has gotten a head start the past two Septembers. Justin Wilson is another product of the farm system. Francisco Liriano was a headlining free-agent signing, and Jonathan Sanchez was a lower-profile get on the market. Andy Oliver came from Detroit in a minor trade.

That leaves only perhaps the darkest horse of them all, but all the same one that might be in the middle of the pack as they turn into the stretch: Kris Johnson. Yes, the same Johnson who, since being a the No. 40 overall Draft pick of Boston in 2006, has logged zero innings in the Majors and 782 2/3 in the Minors.

But wait: This is also the same guy who in 2012, his seventh year in the pros but first in the Pittsburgh organization, finally got it; and kept getting it in the Dominican Winter League.

"I think I've kept doing the same things. Guess it all kinda came together," Johnson, 28, said.

Perhaps it was simply a Red Sox thing. As a Boston farmhand, Johnson compiled an ERA of 5.10 until his mid-2011 release. He hooked on with the Kansas City T-Bones of the independent American Association for the rest of that season, and posted a 3.23 ERA in 16 starts. That got him a shot with the Pirates, and he had a 3.19 ERA in splitting '12 between Double-A Altoona and Triple-A Indianapolis.

"Every time he pitched," manager Clint Hurdle said, "somebody would say, 'Who is that guy?' So you watched him. He's been challenged in the past, and he's grown into himself."

That introduction to the Pirates was still a mere tuneup for Johnson's run with Dominican champion Escogido that read like a typo: In 11 games, including nine starts, he allowed 37 hits -- none of them home runs -- in 59 1/3 innings, with an ERA of 0.91 and 50 strikeouts to 13 walks. That highly-competitive winter league included numerous big leaguers and the cream of the native talent.

"And Johnson dominated in every game," said Dominican teammate Starling Marte, who himself starred for Escogido and was named MVP of the playoffs. "His control was amazing, and nobody could hit him."

"It definitely builds your confidence when you do well down there," Johnson said. "There was a lot of great competition against some Major League mainstays. I loved it."

"He went down there and was more than competitive," Hurdle said. "He pretty much dominated the last few weeks. He made pitches, he controlled bat speed, he pounded the zone and executed to finish pitches. There wasn't a lot of hard contact [off him]. His confidence has never been higher."

Nor, one must assume, have his chances of making a big league staff. Considering how Johnson has grown to trust his stuff in the strike zone, the Pirates are hoping to have another one of those traditionally slow- and late-developing left-handers. That runs in the southpaw family: Certainly not to make comparisons, only a point, but Randy Johnson did not post double-figure wins until the season in which he turned 27, and Kenny Rogers didn't become a regular big league starter until 28.

"You gotta like the perseverance and the resiliency he's shown," Hurdle said of Johnson.

Puzzlingly, Johnson can't pinpoint his turnaround, other than reasoning most of it has been mental, since he altered neither his approach nor his repertoire.

"Maybe it was just the accumulation of having seen a lot of pitching coaches, and picking up something from each," he said. "My strikeout-to-walk ratio with Boston wasn't great, and it all changed last year, especially in winter league. I focused on command instead of just trying to throw the ball by guys.

"And when I saw the success I was getting with that, it became a matter of trusting your training and your body and your stuff."

Another thing that changed last year was the manner in which Johnson was deployed. Between the two stops in the chain, he made 13 starts and 22 relief appearances. Previously, he'd predominantly been a starter, with only 10 relief outings mixed with his 119 starts as a Red Sox prospect.

"I did a little bit of both last year. It's always nice to have a variety of things you can do," said Johnson, who came to camp to make the team, not to talk about how he preferred to do that. "Whatever the team needs. If it's, 'Hey, we need you to go get this lefty,' fine."

The Pirates got this lefty, and they are intrigued to see how far he can go get 'em.