MESA, Ariz. – The Cubs bet $155 million that it won’t disrupt their big plans for October the next few years.

And Jon Lester seems confident it will remain the “non-issue” it has been for much of his career – then looks around for a place to “knock on wood” whenever he mentions it.

But a bone chip lurks in Lester’s pitching elbow, and nobody can know when or if it will break free and suddenly become an injury that requires surgery.

Yahoo Sports baseball columnist Jeff Passan first reported the existence of the bone chip in an exhaustively researched new book, The Arm, to be published the first week of April – as the Cubs, coincidentally, open one of the most anticipated, significant seasons in franchise history.

Passan describes an MRI Lester’s agents arranged after the 2014 season that produced a largely glowing report on the shoulder and elbow, except that “a little grenade floated near his ligament, and at some point it would warrant surgery.”

In a conversation with the Sun-Times on Friday, Lester talked with ease about the subject, and said he figures he has pitched much of his career with the chip and expects to continue to manage it without seeking offseason surgery.

“It’s just a matter of hopefully it stays put, and we don’t have any worry about it,” Lester said. “And then if it does become a concern, if I start having inflammation or missing starts because of it, then that’s when we’ll probably sit down and talk to somebody about getting it removed.

“As of now, knock on wood, I haven’t had any concern with it.”

The Cubs’ front office, which spent a decade with Lester in Boston, got the same results with their own MRI after the team and Lester agreed on a six-year, $155 million deal, and have treated it as essentially a benign condition.

“We did a very thorough exam including imaging of the shoulder and elbow,” team president Theo Epstein said Friday. “We were really quite pleased with the results, as Jon compared very favorably with most of the free agent pitchers we have examined and MRI’d over many years.

“Virtually all pitchers have some wear and tear on their shoulders and elbows, and Jon’s imperfections were very manageable. He remains very consistent, as we hoped, throwing 200-plus quality innings yet again last season.”

Lester admitted “it was kind of a surprise” to learn of the chip after he’d had his personal MRI, even though trainers had suggested to him for years he might have something in the elbow.

“With certain things throughout the year that come up, they’re like, yeah, you probably have something in there,” he said.

While Passan writes that the chip bothered Lester early every spring before his arm worked into shape, last spring’s “dead-arm” issue was completely unrelated, Lester said.

Despite assurances that he likely could continue to pitch without serious issue, and after additional medical opinions that confirmed the first, Lester held back the information about the chip during the free agency process, fearing what it might do to his market.

“Going through that process you never know,” he said. “You just hear different stories from different people, and stuff that gets out. You definitely don’t want to be that guy where you work your whole life to get to that point and have a chance at something that I was fortunate enough to sign and it get ruined by a bone chip.”

The Baltimore Orioles, alone, backed out of a two-year agreement with reliever Grant Balfour after a physical the winter before Lester’s free agency, and reduced their offer to pitcher Yovani Gallardo last month after a physical.

“But at the same time I was realistic to the fact that you put any pitcher in a [MRI] tube, you’re going to have something,” he said.

“Luckily, my shoulder was pretty well intact, and my ligament looked good – I guess as good as a 31-year-old pitcher can look,” he added with a laugh. “As far as team doctors were concerned, or any other doctor that we got an opinion from, there wasn’t too much of a concern over it.”

Bone chips and bone spurs are not uncommon. There is no maintenance program for them, beyond treatment and anti-inflammatories if they flare up.

“It’s kind of one of those deals if it’s not bothering you, don’t mess with it,” said Lester, who doesn’t like the potential risk, or the rehab, associated with preventative surgery.

“You start getting cut on and doing rehab,” he said, “and that’s when maybe they’re in there, taking that bone chip out, and it puts more stress on something else. You don’t know. If it ain’t broke don’t fix it type thing.”

So far, he has produced results to back up his confidence. He has made 31 starts or more in eight consecutive years, surpassing 200 innings in seven of those seasons (191 2/3 in the other).

He’s also pitched deep enough into October to win two World Series, and pitched well enough to make three All-Star teams.

But a bone chip in a pitching elbow is only benign until the moment it suddenly is not, until it breaks free, shifts or floats into an area that makes pitching too painful or damaging to the elbow.

If anything, the revelation of a “little grenade” in Lester’s elbow underscores the inherent risk with big-money pitchers that Epstein discussed during Lester’s introductory media conference 15 months ago in Chicago.

“Historically, nine-figure deals for starting pitchers in their 30s haven’t worked out,” he said. “There are a lot of mitigating factors in there, but I’m not going to say it’s without risk, because it’s not without risk. Contracts like this always carry risk

“We’ve been around Jon since he was 18. So I know exactly what shoulder program he’s been on since he was 18. I know how well he’s executed that shoulder program, how diligent he was. I know what his MRIs look like.”

And he still bet $155 million on that first, huge, left-handed piece of the ramp-up phase of the Cubs’ long-term, championship plan.

“It’s just a matter of what you can manage and what you can deal with and pitch with,” Lester said. “I keep saying knock on wood, but it’s been a non-issue.”